R600/SI: Make sure M0 is loaded for V_INTERP_MOV_F32

NOTE: This is a candidate for the Mesa stable branch.

Reviewed-by: Tom Stellard <thomas.stellard@amd.com>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@175733 91177308-0d34-0410-b5e6-96231b3b80d8