drm/amd/display: expand plane caps to include fp16 and scaling capability

[why]
there are some scaling capabilities such as fp16 which are known to be unsupported
on a given ASIC.  exposing these static capabilities allows much simpler implementation
for OS interfaces which require to report such static capabilities to reduce the
number of dynamic validation calls

[how]
refactor the existing plane caps to be more extensible, and add fp16 and scaling
capabilities

Signed-off-by: Jun Lei <Jun.Lei@amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Acked-by: Bhawanpreet Lakha &lt;Bhawanpreet <Lakha@amd.com>
Acked-by: Harry Wentland <Harry.Wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>