[llvm] [RISCV] Add helper function getVecPolicyOpNum in RISCVInsertVSETVLI.cpp. NFC. (PR #161476)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clang-armv8-quick` running on `linaro-clang-armv8-quick` while building `llvm` at step 5 "ninja check 1".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/154/builds/22213

<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 'Clangd Unit Tests :: ./ClangdTests/161/333' FAILED ********************
Script(shard):
--
GTEST_OUTPUT=json:/home/tcwg-buildbot/worker/clang-armv8-quick/stage1/tools/clang/tools/extra/clangd/unittests/./ClangdTests-Clangd Unit Tests-2491829-161-333.json GTEST_SHUFFLE=0 GTEST_TOTAL_SHARDS=333 GTEST_SHARD_INDEX=161 /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/tools/clang/tools/extra/clangd/unittests/./ClangdTests
--

Note: This is test shard 162 of 333.
[==========] Running 4 tests from 4 test suites.
[----------] Global test environment set-up.
[----------] 1 test from CompletionTest
[ RUN      ] CompletionTest.MergeMacrosFromIndexAndSema
Built preamble of size 341892 for file /clangd-test/foo.cpp version null in 0.04 seconds
Code complete: fuzzyFind({
  "AnyScope": false,
  "Limit": null,
  "PreferredTypes": [],
  "ProximityPaths": [
    "/clangd-test/foo.cpp"
  ],
  "Query": "Clangd_Macro_T",
  "RestrictForCodeCompletion": true,
  "Scopes": [
    ""
  ]
})
Code complete: sema context TopLevel, query scopes [] (AnyScope=false), expected type <none>
Code complete: 1 results from Sema, 1 from Index, 1 matched, 0 from identifiers, 1 returned.
[       OK ] CompletionTest.MergeMacrosFromIndexAndSema (57 ms)
[----------] 1 test from CompletionTest (57 ms total)

[----------] 1 test from FileIndexTest
[ RUN      ] FileIndexTest.MacroRefs
Built preamble of size 342420 for file /clangd-test/test.cc version null in 0.01 seconds
indexed file AST for /clangd-test/test.cc version null:
  symbol slab: 2 symbols, 4444 bytes
  ref slab: 3 symbols, 4 refs, 4232 bytes
  relations slab: 0 relations, 12 bytes
Build dynamic index for main-file symbols with estimated memory usage of 10844 bytes
Built preamble of size 342420 for file /clangd-test/test.cc version null in 0.01 seconds
indexed preamble AST for /clangd-test/test.cc version null:
  symbol slab: 3 symbols, 4584 bytes
  ref slab: 0 symbols, 0 refs, 72 bytes
  relations slab: 0 relations, 12 bytes
Built preamble of size 342420 for file /clangd-test/test.cc version null in 0.01 seconds
indexed preamble AST for /clangd-test/test.cc version null:
  symbol slab: 3 symbols, 4584 bytes
  ref slab: 0 symbols, 0 refs, 72 bytes
  relations slab: 0 relations, 12 bytes
[       OK ] FileIndexTest.MacroRefs (87 ms)
[----------] 1 test from FileIndexTest (88 ms total)
...

```

</details>

https://github.com/llvm/llvm-project/pull/161476