[llvm] [RISCV] Remove codegen for vp_{u,s}{add,sub}sat (PR #191639)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `llvm-clang-x86_64-expensive-checks-ubuntu` running on `as-builder-4` while building `llvm` at step 7 "test-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/187/builds/18909

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 7 (test-check-all) failure: Test just built components: check-all completed (failure)
******************** TEST 'LLVM :: CodeGen/X86/basic-block-sections-code-prefetch.ll' FAILED ********************
Exit Code: 1

Command Output (stdout):
--
# RUN: at line 4
echo 'v1' > /home/buildbot/worker/as-builder-4/ramdisk/expensive-checks/build/test/CodeGen/X86/Output/basic-block-sections-code-prefetch.ll.tmp
# executed command: echo v1
# RUN: at line 5
echo 'f foo' >> /home/buildbot/worker/as-builder-4/ramdisk/expensive-checks/build/test/CodeGen/X86/Output/basic-block-sections-code-prefetch.ll.tmp
# executed command: echo 'f foo'
# RUN: at line 6
echo 't 0,0' >> /home/buildbot/worker/as-builder-4/ramdisk/expensive-checks/build/test/CodeGen/X86/Output/basic-block-sections-code-prefetch.ll.tmp
# executed command: echo 't 0,0'
# RUN: at line 7
echo 't 1,0' >> /home/buildbot/worker/as-builder-4/ramdisk/expensive-checks/build/test/CodeGen/X86/Output/basic-block-sections-code-prefetch.ll.tmp
# executed command: echo 't 1,0'
# RUN: at line 8
echo 't 1,1' >> /home/buildbot/worker/as-builder-4/ramdisk/expensive-checks/build/test/CodeGen/X86/Output/basic-block-sections-code-prefetch.ll.tmp
# executed command: echo 't 1,1'
# RUN: at line 9
echo 't 2,1' >> /home/buildbot/worker/as-builder-4/ramdisk/expensive-checks/build/test/CodeGen/X86/Output/basic-block-sections-code-prefetch.ll.tmp
# executed command: echo 't 2,1'
# RUN: at line 10
echo 't 3,0' >> /home/buildbot/worker/as-builder-4/ramdisk/expensive-checks/build/test/CodeGen/X86/Output/basic-block-sections-code-prefetch.ll.tmp
# executed command: echo 't 3,0'
# RUN: at line 11
echo 't 3,1' >> /home/buildbot/worker/as-builder-4/ramdisk/expensive-checks/build/test/CodeGen/X86/Output/basic-block-sections-code-prefetch.ll.tmp
# executed command: echo 't 3,1'
# RUN: at line 12
echo 'i 3,0 bar,0,0' >> /home/buildbot/worker/as-builder-4/ramdisk/expensive-checks/build/test/CodeGen/X86/Output/basic-block-sections-code-prefetch.ll.tmp
# executed command: echo 'i 3,0 bar,0,0'
# RUN: at line 13
echo 'i 2,1 foo,1,0' >> /home/buildbot/worker/as-builder-4/ramdisk/expensive-checks/build/test/CodeGen/X86/Output/basic-block-sections-code-prefetch.ll.tmp
# executed command: echo 'i 2,1 foo,1,0'
# RUN: at line 14
echo 'i 1,1 extfunc,5,5' >> /home/buildbot/worker/as-builder-4/ramdisk/expensive-checks/build/test/CodeGen/X86/Output/basic-block-sections-code-prefetch.ll.tmp
# executed command: echo 'i 1,1 extfunc,5,5'
# RUN: at line 15
echo 'i 1,1 bar,0,0' >> /home/buildbot/worker/as-builder-4/ramdisk/expensive-checks/build/test/CodeGen/X86/Output/basic-block-sections-code-prefetch.ll.tmp
# executed command: echo 'i 1,1 bar,0,0'
# RUN: at line 16
echo 'f bar' >> /home/buildbot/worker/as-builder-4/ramdisk/expensive-checks/build/test/CodeGen/X86/Output/basic-block-sections-code-prefetch.ll.tmp
# executed command: echo 'f bar'
# RUN: at line 17
echo 't 0,0' >> /home/buildbot/worker/as-builder-4/ramdisk/expensive-checks/build/test/CodeGen/X86/Output/basic-block-sections-code-prefetch.ll.tmp
# executed command: echo 't 0,0'
# RUN: at line 18
echo 't 21,1' >> /home/buildbot/worker/as-builder-4/ramdisk/expensive-checks/build/test/CodeGen/X86/Output/basic-block-sections-code-prefetch.ll.tmp
# executed command: echo 't 21,1'
...

```

</details>

https://github.com/llvm/llvm-project/pull/191639