drm/amdgpu: Add XCP IP callback funcs for each IP

Initialize with the IP specific functions needed for GFXHUB, GFX and
SDMA.

Signed-off-by: Lijo Lazar <lijo.lazar@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>