[llvm] [NFC][RISCV] Move Zvfbf* relative stuffs to RISCVInstrInfoZvfbf.td (PR #159619)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `cross-project-tests-sie-ubuntu-dwarf5` running on `doug-worker-1b` while building `llvm` at step 5 "build-unified-tree".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/163/builds/26782

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

```
Step 5 (build-unified-tree) failure: build (failure)
0.036 [148/4/1] Generating VCSRevision.h
0.036 [148/3/2] Generating VCSVersion.inc
0.037 [147/3/3] Running utility command for liblldb-header-staging
0.769 [147/2/4] Building CXX object tools/lldb/source/Version/CMakeFiles/lldbVersion.dir/Version.cpp.o
0.784 [146/2/5] Linking CXX static library lib/liblldbVersion.a
1.586 [146/1/6] Building RISCVTargetParserDef.inc...
FAILED: include/llvm/TargetParser/RISCVTargetParserDef.inc /home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/build/include/llvm/TargetParser/RISCVTargetParserDef.inc 
cd /home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/build/include/llvm/TargetParser && /home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/build/bin/llvm-min-tblgen -gen-riscv-target-def -I/home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/llvm-project/llvm/include/llvm/TargetParser -I/home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/llvm-project/llvm/lib/Target/RISCV -I/home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/build/include -I/home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/llvm-project/llvm/include /home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/llvm-project/llvm/lib/Target/RISCV/RISCV.td --write-if-changed -o /home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/build/include/llvm/TargetParser/RISCVTargetParserDef.inc
Included from /home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/llvm-project/llvm/lib/Target/RISCV/RISCV.td:36:
Included from /home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/llvm-project/llvm/lib/Target/RISCV/RISCVInstrInfo.td:2344:
Included from /home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/llvm-project/llvm/lib/Target/RISCV/RISCVInstrInfoV.td:1842:
/home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/llvm-project/llvm/lib/Target/RISCV/RISCVInstrInfoZvfbf.td:39:19: error: Variable not defined: 'HasStdExtZvfbfmin'
let Predicates = [HasStdExtZvfbfmin] in {
                  ^
ninja: build stopped: subcommand failed.

```

</details>

https://github.com/llvm/llvm-project/pull/159619