This disambiguates depth 16 formats, such as ARGB1555 and ARGB4444,
and depth 32 formats such as ARGB2101010 and ARGB8888.

This patch also adds support for depth 30 (XRGB2101010) framebuffers.
Signed-off-by: Fredrik Höglund <fredrik@kde.org>
Reviewed-by: Mario Kleiner <mario.kleiner.de@gmail.com>
Tested-by: Mario Kleiner <mario.kleiner.de@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>