drm/amd/display: add nv12 bounding box

This was included in gpu_info firmware, move it into the
driver for consistency with other nv1x parts.

Link: https://gitlab.freedesktop.org/drm/amd/-/issues/2318
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>