[Why]
Cursor size can update without MALL cache update.
Update the register on cursor attribute as well.

[How]
Update cursor MALL cache on cursor attribute update.
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Reviewed-by: Alvin Lee <Alvin.Lee2@amd.com>
Acked-by: Alan Liu <HaoPing.Liu@amd.com>
Signed-off-by: Chris Park <chris.park@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>