[llvm] [PowerPC][LLC] Utilize PPC::getNormalizedPPCTargetCPU() to set CPU (PR #113943)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `premerge-monolithic-linux` running on `premerge-linux-1` while building `llvm` at step 7 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/153/builds/13573

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

```
Step 7 (test-build-unified-tree-check-all) failure: test (failure)
******************** TEST 'LLVM :: CodeGen/PowerPC/stack-guard-global.ll' FAILED ********************
Exit Code: 1

Command Output (stderr):
--
RUN: at line 2: /build/buildbot/premerge-monolithic-linux/build/bin/llc -mtriple=powerpc64 -verify-machineinstrs < /build/buildbot/premerge-monolithic-linux/llvm-project/llvm/test/CodeGen/PowerPC/stack-guard-global.ll      | /build/buildbot/premerge-monolithic-linux/build/bin/FileCheck /build/buildbot/premerge-monolithic-linux/llvm-project/llvm/test/CodeGen/PowerPC/stack-guard-global.ll --check-prefixes=BE64
+ /build/buildbot/premerge-monolithic-linux/build/bin/FileCheck /build/buildbot/premerge-monolithic-linux/llvm-project/llvm/test/CodeGen/PowerPC/stack-guard-global.ll --check-prefixes=BE64
+ /build/buildbot/premerge-monolithic-linux/build/bin/llc -mtriple=powerpc64 -verify-machineinstrs
/build/buildbot/premerge-monolithic-linux/llvm-project/llvm/test/CodeGen/PowerPC/stack-guard-global.ll:17:14: error: BE64-NEXT: is not on the line after the previous match
; BE64-NEXT: std 30, 128(31) # 8-byte Folded Spill
             ^
<stdin>:22:2: note: 'next' match was here
 std 30, 128(31) # 8-byte Folded Spill
 ^
<stdin>:19:15: note: previous match ended here
 std 0, 160(1)
              ^
<stdin>:20:1: note: non-matching line after previous match is here
 sldi 3, 3, 2
^

Input file: <stdin>
Check file: /build/buildbot/premerge-monolithic-linux/llvm-project/llvm/test/CodeGen/PowerPC/stack-guard-global.ll

-dump-input=help explains the following input dump.

Input was:
<<<<<<
         .
         .
         .
        17:  stdu 1, -144(1) 
        18:  mr 31, 1 
        19:  std 0, 160(1) 
        20:  sldi 3, 3, 2 
        21:  addi 3, 3, 15 
        22:  std 30, 128(31) # 8-byte Folded Spill 
next:17      !~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  error: match on wrong line
        23:  addis 30, 2, __stack_chk_guard at toc@ha 
        24:  rldicr 3, 3, 0, 59 
        25:  neg 3, 3 
        26:  ld 4, __stack_chk_guard at toc@l(30) 
        27:  std 4, 120(31) 
         .
         .
         .
>>>>>>

--

...

```

</details>

https://github.com/llvm/llvm-project/pull/113943