[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 `llvm-x86_64-debian-dylib` running on `gribozavr4` while building `llvm` at step 7 "test-build-unified-tree-check-llvm".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/60/builds/11782

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

```
Step 7 (test-build-unified-tree-check-llvm) failure: test (failure)
******************** TEST 'LLVM :: CodeGen/PowerPC/uaddo-64.ll' FAILED ********************
Exit Code: 1

Command Output (stderr):
--
RUN: at line 2: /b/1/llvm-x86_64-debian-dylib/build/bin/llc < /b/1/llvm-x86_64-debian-dylib/llvm-project/llvm/test/CodeGen/PowerPC/uaddo-64.ll -mtriple=powerpc64-unknown-linux-gnu | /b/1/llvm-x86_64-debian-dylib/build/bin/FileCheck /b/1/llvm-x86_64-debian-dylib/llvm-project/llvm/test/CodeGen/PowerPC/uaddo-64.ll
+ /b/1/llvm-x86_64-debian-dylib/build/bin/llc -mtriple=powerpc64-unknown-linux-gnu
+ /b/1/llvm-x86_64-debian-dylib/build/bin/FileCheck /b/1/llvm-x86_64-debian-dylib/llvm-project/llvm/test/CodeGen/PowerPC/uaddo-64.ll
/b/1/llvm-x86_64-debian-dylib/llvm-project/llvm/test/CodeGen/PowerPC/uaddo-64.ll:29:15: error: CHECK-NEXT: is not on the line after the previous match
; CHECK-NEXT: addze 3, 6
              ^
<stdin>:43:2: note: 'next' match was here
 addze 3, 6
 ^
<stdin>:41:14: note: previous match ended here
 addc 4, 3, 4
             ^
<stdin>:42:1: note: non-matching line after previous match is here
 std 4, 0(5)
^

Input file: <stdin>
Check file: /b/1/llvm-x86_64-debian-dylib/llvm-project/llvm/test/CodeGen/PowerPC/uaddo-64.ll

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

Input was:
<<<<<<
         .
         .
         .
        38:  .cfi_startproc 
        39: # %bb.0: # %entry 
        40:  li 6, 0 
        41:  addc 4, 3, 4 
        42:  std 4, 0(5) 
        43:  addze 3, 6 
next:29      !~~~~~~~~~  error: match on wrong line
        44:  blr 
        45:  .long 0 
        46:  .quad 0 
        47: .Lfunc_end1: 
        48:  .size add_overflow, .Lfunc_end1-.Lfunc_begin1 
         .
         .
         .
>>>>>>

--

...

```

</details>

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