R600/SI: Try to keep i32 mul on SALU

Also fix bug this exposed where when legalizing an immediate
operand, a v_mov_b32 would be created with a VSrc dest register.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217108 91177308-0d34-0410-b5e6-96231b3b80d8
5 files changed