AMDGPU: Remove incorrect assertion

I'm still not sure under what circumstances the offset here is non-0,
but private memory is not limited to 27-bits.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@272337 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed