drm/amd/display: correct clip x assignment in cursor programming

drm/amd/display: correct clip x assignment in cursor programming

[why&how]
primary planes for external displays getting incorrect clip
values, detect such a scenario and pass correct parameters

Reviewed-by: Ovidiu (Ovi) Bunea <ovidiu.bunea@amd.com>
Signed-off-by: Ausef Yousof <auyousof@amd.com>
Signed-off-by: Matthew Stewart <matthew.stewart2@amd.com>
Tested-by: Dan Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>