drm/amdgpu: add video decode/encode cap tables and asic callbacks (v3)

For each asic family.  Will be used to populate tables
for the new INFO ioctl query.

v2: add max_pixels_per_frame to handle the portrait case
v3: fix copy paste typos

Reviewed-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Leo Liu <leo.liu@amd.com> (v1)
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>