drm/amd/display: SW cursor fallback for SubVP

[Description]
Leverage SW cursor fall back for SubVP when the cursor is too big. We
want to take advantage of being able to fallback to SW cursor when
possible because it's not worth it to disable MCLK switching because the
cursor is slightly too big.

Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Reviewed-by: Aurabindo Pillai <Aurabindo.Pillai@amd.com>
Acked-by: Pavle Kotarac <Pavle.Kotarac@amd.com>
Signed-off-by: Alvin Lee <Alvin.Lee2@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>