[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 `clang-x86_64-debian-fast` running on `gribozavr4` while building `llvm` at step 6 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/56/builds/11333

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

```
Step 6 (test-build-unified-tree-check-all) failure: test (failure)
******************** TEST 'LLVM :: CodeGen/PowerPC/stack-guard-tls.ll' FAILED ********************
Exit Code: 1

Command Output (stderr):
--
RUN: at line 2: /b/1/clang-x86_64-debian-fast/llvm.obj/bin/llc -mtriple=powerpc64 -verify-machineinstrs < /b/1/clang-x86_64-debian-fast/llvm.src/llvm/test/CodeGen/PowerPC/stack-guard-tls.ll      | /b/1/clang-x86_64-debian-fast/llvm.obj/bin/FileCheck /b/1/clang-x86_64-debian-fast/llvm.src/llvm/test/CodeGen/PowerPC/stack-guard-tls.ll --check-prefixes=BE64
+ /b/1/clang-x86_64-debian-fast/llvm.obj/bin/FileCheck /b/1/clang-x86_64-debian-fast/llvm.src/llvm/test/CodeGen/PowerPC/stack-guard-tls.ll --check-prefixes=BE64
+ /b/1/clang-x86_64-debian-fast/llvm.obj/bin/llc -mtriple=powerpc64 -verify-machineinstrs
/b/1/clang-x86_64-debian-fast/llvm.src/llvm/test/CodeGen/PowerPC/stack-guard-tls.ll:35:14: error: BE64-NEXT: is not on the line after the previous match
; BE64-NEXT: ld 31, -8(1)
             ^
<stdin>:39:2: note: 'next' match was here
 ld 31, -8(1)
 ^
<stdin>:37:13: note: previous match ended here
 ld 0, 16(1)
            ^
<stdin>:38:1: note: non-matching line after previous match is here
 mtlr 0
^

Input file: <stdin>
Check file: /b/1/clang-x86_64-debian-fast/llvm.src/llvm/test/CodeGen/PowerPC/stack-guard-tls.ll

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

Input was:
<<<<<<
         .
         .
         .
        34:  bne 0, .LBB0_2 
        35: # %bb.1: 
        36:  ld 1, 0(1) 
        37:  ld 0, 16(1) 
        38:  mtlr 0 
        39:  ld 31, -8(1) 
next:35      !~~~~~~~~~~~  error: match on wrong line
        40:  blr 
        41: .LBB0_2: 
        42:  bl __stack_chk_fail 
        43:  nop 
        44:  .long 0 
         .
         .
         .
>>>>>>

--

...

```

</details>

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