drm/amd/display: dce60_hw_sequencer: add DCE6 specific .cursor_lock

[Why]
kernel WARNING due to use of .cursor_lock = dce_pipe_control_lock inherited by dce110

[How]
DCE6 set .cursor_lock = dce60_pipe_control_lock

Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Mauro Rossi <issor.oruam@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>