drm/amd/display: Added power down for DCN10

[Why]
The change of setting a timer callback on boot for 10 seconds is still
working, just lacked power down for DCN10.

[How]
Added power down for DCN10.
Tested-by: NDaniel Wheeler <daniel.wheeler@amd.com>
Reviewed-by: NAnthony Koo <Anthony.Koo@amd.com>
Acked-by: NRodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: NDerek Lai <Derek.Lai@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/dcn10/dcn10_init.c

@@ -78,6 +78,7 @@ static const struct hw_sequencer_funcs dcn10_funcs = {
 	.get_clock = dcn10_get_clock,
 	.get_vupdate_offset_from_vsync = dcn10_get_vupdate_offset_from_vsync,
 	.calc_vupdate_position = dcn10_calc_vupdate_position,
+	.power_down = dce110_power_down,
 	.set_backlight_level = dce110_set_backlight_level,
 	.set_abm_immediate_disable = dce110_set_abm_immediate_disable,
 	.set_pipe = dce110_set_pipe,