amdgpu/dc: inline a bunch of the fixed 31_32 helpers.

This decreases code size by a few hundred bytes.

Signed-off-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>