drm/amd/display: Turn off internal backlight when plugging external monitor

[why]
For VG, we want to turn off power/backlight of the intenral panel when
plugging in external monitor and going to "external monitor only" mode.

[how]
For turning off power of the internal panel, ignore the config flag whic
bypasses power sequencing for eDP panels.
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Reviewed-by: Charlene Liu <Charlene.Liu@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Sung Joon Kim <sungkim@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c

@@ -7275,8 +7275,7 @@ void dp_disable_link_phy(struct dc_link *link, const struct link_resource *link_
 			link->dc->hwss.edp_backlight_control(link, false);
 		if (link_hwss->ext.disable_dp_link_output)
 			link_hwss->ext.disable_dp_link_output(link, link_res, signal);
-		if (!link->dc->config.edp_no_power_sequencing)
-			link->dc->hwss.edp_power_control(link, false);
+		link->dc->hwss.edp_power_control(link, false);
 	} else {
 		if (dmcu != NULL && dmcu->funcs->lock_phy)
 			dmcu->funcs->lock_phy(dmcu);