AMDGPU: Make flat_scratch name consistent

The printed name and the parsed assembler names weren't the same.
I'm not sure which name SC prints these as, but I think it's this one.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@252010 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed