[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 `llvm-clang-x86_64-sie-win` running on `sie-win-worker` while building `llvm` at step 4 "clean-build-dir".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/46/builds/23599

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

```
Step 4 (clean-build-dir) failure: Delete failed. (failure)
Step 6 (build-unified-tree) failure: build (failure)
...
[831/5045] Building RC object tools\remarks-shlib\CMakeFiles\Remarks.dir\__\__\resources\windows_version_resource.rc.res
[832/5045] Linking CXX static library lib\LLVMOrcShared.lib
[833/5045] Linking CXX static library lib\LLVMTableGenCommon.lib
[834/5045] Linking CXX static library lib\clangSupport.lib
[835/5045] Building CXX object third-party\benchmark\src\CMakeFiles\benchmark.dir\perf_counters.cc.obj
[836/5045] Linking CXX static library lib\DynamicLibraryLib.lib
[837/5045] Linking CXX static library lib\LLVMRemarks.lib
[838/5045] Building CXX object third-party\benchmark\src\CMakeFiles\benchmark.dir\statistics.cc.obj
[839/5045] Linking CXX shared module unittests\Support\DynamicLibrary\PipSqueak.dll
[840/5045] Building RISCVTargetParserDef.inc...
FAILED: include/llvm/TargetParser/RISCVTargetParserDef.inc 
cmd.exe /C "cd /D Z:\b\llvm-clang-x86_64-sie-win\build\include\llvm\TargetParser && Z:\b\llvm-clang-x86_64-sie-win\build\bin\llvm-min-tblgen.exe -gen-riscv-target-def -IZ:/b/llvm-clang-x86_64-sie-win/llvm-project/llvm/include/llvm/TargetParser -IZ:/b/llvm-clang-x86_64-sie-win/llvm-project/llvm/lib/Target/RISCV -IZ:/b/llvm-clang-x86_64-sie-win/build/include -IZ:/b/llvm-clang-x86_64-sie-win/llvm-project/llvm/include --long-string-literals=0 Z:/b/llvm-clang-x86_64-sie-win/llvm-project/llvm/lib/Target/RISCV/RISCV.td --write-if-changed -o Z:/b/llvm-clang-x86_64-sie-win/build/include/llvm/TargetParser/RISCVTargetParserDef.inc"
Included from Z:/b/llvm-clang-x86_64-sie-win/llvm-project/llvm/lib/Target/RISCV/RISCV.td:36:
Included from Z:/b/llvm-clang-x86_64-sie-win/llvm-project/llvm/lib/Target/RISCV\RISCVInstrInfo.td:2344:
Included from Z:/b/llvm-clang-x86_64-sie-win/llvm-project/llvm/lib/Target/RISCV\RISCVInstrInfoV.td:1842:
Z:/b/llvm-clang-x86_64-sie-win/llvm-project/llvm/lib/Target/RISCV\RISCVInstrInfoZvfbf.td:39:19: error: Variable not defined: 'HasStdExtZvfbfmin'

let Predicates = [HasStdExtZvfbfmin] in {

                  ^

[841/5045] Linking CXX shared module unittests\Support\DynamicLibrary\SecondLib.dll
[842/5045] Linking CXX executable bin\clang-tidy-confusable-chars-gen.exe
[843/5045] Linking CXX static library lib\benchmark.lib
[844/5045] Linking CXX executable bin\reduce-chunk-list.exe
[845/5045] Linking CXX executable bin\clang-tblgen.exe
[846/5045] Linking CXX executable bin\KillTheDoctor.exe
[847/5045] Linking CXX executable bin\llvm-undname.exe
[848/5045] Linking CXX executable bin\llvm-tblgen.exe
[849/5045] Linking CXX executable bin\llvm-opt-report.exe
[850/5045] Linking CXX shared library bin\Remarks.dll
[851/5045] Linking CXX executable bin\llvm-remarkutil.exe
ninja: build stopped: subcommand failed.

```

</details>

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