[llvm] [AMDGPU] Remove unused True16 patterns. (PR #163784)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clang-m68k-linux-cross` running on `suse-gary-m68k-cross` while building `llvm` at step 5 "ninja check 1".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/27/builds/17757

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

```
Step 5 (ninja check 1) failure: stage 1 checked (failure)
******************** TEST 'LLVM :: ExecutionEngine/JITLink/x86-64/MachO_cstring_section_alignment.s' FAILED ********************
Exit Code: 1

Command Output (stdout):
--
# RUN: at line 2
/var/lib/buildbot/workers/suse-gary-m68k-cross/clang-m68k-linux-cross/stage1/bin/llvm-mc -triple=x86_64-apple-macos10.9 -filetype=obj -o /var/lib/buildbot/workers/suse-gary-m68k-cross/clang-m68k-linux-cross/stage1/test/ExecutionEngine/JITLink/x86-64/Output/MachO_cstring_section_alignment.s.tmp /var/lib/buildbot/workers/suse-gary-m68k-cross/clang-m68k-linux-cross/llvm/llvm/test/ExecutionEngine/JITLink/x86-64/MachO_cstring_section_alignment.s
# executed command: /var/lib/buildbot/workers/suse-gary-m68k-cross/clang-m68k-linux-cross/stage1/bin/llvm-mc -triple=x86_64-apple-macos10.9 -filetype=obj -o /var/lib/buildbot/workers/suse-gary-m68k-cross/clang-m68k-linux-cross/stage1/test/ExecutionEngine/JITLink/x86-64/Output/MachO_cstring_section_alignment.s.tmp /var/lib/buildbot/workers/suse-gary-m68k-cross/clang-m68k-linux-cross/llvm/llvm/test/ExecutionEngine/JITLink/x86-64/MachO_cstring_section_alignment.s
# RUN: at line 3
/var/lib/buildbot/workers/suse-gary-m68k-cross/clang-m68k-linux-cross/stage1/bin/llvm-jitlink -num-threads=0 -debug-only=jitlink -noexec /var/lib/buildbot/workers/suse-gary-m68k-cross/clang-m68k-linux-cross/stage1/test/ExecutionEngine/JITLink/x86-64/Output/MachO_cstring_section_alignment.s.tmp 2>&1               | /var/lib/buildbot/workers/suse-gary-m68k-cross/clang-m68k-linux-cross/stage1/bin/FileCheck /var/lib/buildbot/workers/suse-gary-m68k-cross/clang-m68k-linux-cross/llvm/llvm/test/ExecutionEngine/JITLink/x86-64/MachO_cstring_section_alignment.s
# executed command: /var/lib/buildbot/workers/suse-gary-m68k-cross/clang-m68k-linux-cross/stage1/bin/llvm-jitlink -num-threads=0 -debug-only=jitlink -noexec /var/lib/buildbot/workers/suse-gary-m68k-cross/clang-m68k-linux-cross/stage1/test/ExecutionEngine/JITLink/x86-64/Output/MachO_cstring_section_alignment.s.tmp
# note: command had no output on stdout or stderr
# error: command failed with exit status: 1
# executed command: /var/lib/buildbot/workers/suse-gary-m68k-cross/clang-m68k-linux-cross/stage1/bin/FileCheck /var/lib/buildbot/workers/suse-gary-m68k-cross/clang-m68k-linux-cross/llvm/llvm/test/ExecutionEngine/JITLink/x86-64/MachO_cstring_section_alignment.s

--

********************


```

</details>

https://github.com/llvm/llvm-project/pull/163784