drm/amd/display: Clamp dc_cursor_position x_hotspot to prevent integer overflow

drm/amd/display: Clamp dc_cursor_position x_hotspot to prevent integer overflow

why:
Workaround for duplicate cursor. Cursor offsetting via x_hotspot attempts
to write a 32 bit unsigned integer to the 8 bit field CURSOR_HOT_SPOT_X.
This wraps cursor position back into focus if x_hotspot exceeds 8 bits,
making duplicate cursors visible

how:
Clamp x_hotspot before writing to hardware

Reviewed-by: Charlene Liu <charlene.liu@amd.com>
Reviewed-by: Nevenko Stupar <nevenko.stupar@amd.com>
Signed-off-by: Benjamin Nwankwo <Benjamin.Nwankwo@amd.com>
Signed-off-by: Chuanyu Tseng <chuanyu.tseng@amd.com>
Tested-by: Dan Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>