When scaling is enabled, our preference is to scale up to the prefered
(native) mode. This means that hardware timings will be the same across
a modeset.

Therefore, also report mode as changed if source or destination
rectangle is different.
Signed-off-by: Leo (Sunpeng) Li <sunpeng.li@amd.com>
Reviewed-by: Harry Wentland <Harry.Wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>