drm/amd/display: enable ABGR and XBGR formats (v4)

SURFACE_PIXEL_FORMAT_GRPH_ABGR8888 is supported in amd/display/dc/dc_hw_types.h
and the necessary crossbars register controls to swap red and blue channels
are already implemented in drm/amd/display/dc/dce/dce_mem_input.c

(v4) Logic to handle new formats is added only in amdgpu_dm module.

Signed-off-by: Mauro Rossi <issor.oruam@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>