drm/amd/display: Fix hotspot programming during set cursor position.

- Remove x,y hotspot from dc_cursor_attributes. Only program it
  through setPosition.

Signed-off-by: Zeyu Fan <Zeyu.Fan@amd.com>
Acked-by: Harry Wentland <Harry.Wentland@amd.com>
Reviewed-by: Zeyu Fan <Zeyu.Fan@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>