v1i32, v2i32, v8i32 and v16i32.

Only add VGPR register classes for integer vector types, to avoid attempts
copying from VGPR to SGPR registers, which is not possible.

Patch By: Michel Dänzer

Signed-off-by: Michel Dänzer <michel.daenzer@amd.com>
Reviewed-by: Tom Stellard <thomas.stellard@amd.com>
llvm-svn: 174632