drm/amd/display: Add missing MI masks

This will fix the memory Input programing with MST tiled display.
This Fix should fix connectivity problems with MST tiled Display

Signed-off-by: Leon Elazar <leon.elazar@amd.com>
Acked-by: Harry Wentland <Harry.Wentland@amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>