R600/SI: Only use S_WQM_B64 in pixel shaders

This doesn't change any functionality, since we only have two shader
types (compute and pixel) that use local memory.  We're just changing
the logic to match the documentation.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@201096 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed