[Power] Delete redundant test Atomics-32.ll

The test Atomics-32.ll was both redundant (all operations are also checked by
atomics.ll at least) and not actually checking correctness (it was not using
FileCheck, just verifying that the compiler does not crash).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218997 91177308-0d34-0410-b5e6-96231b3b80d8