usb: dwc3: drd: Add support for usb-conn-gpio based usb-role-switch

usb-conn-gpio devices are a subnode of the USB interface controller, which
needs to be populated.
This allows having a non-type-c connector providing dual-role.
Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Link: https://lore.kernel.org/r/20220105071407.2240302-1-alexander.stein@ew.tq-group.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/dwc3/drd.c

@@ -9,6 +9,7 @@
 
 #include <linux/extcon.h>
 #include <linux/of_graph.h>
+#include <linux/of_platform.h>
 #include <linux/platform_device.h>
 #include <linux/property.h>
 
@@ -559,6 +560,18 @@ static int dwc3_setup_role_switch(struct dwc3 *dwc)
 	if (IS_ERR(dwc->role_sw))
 		return PTR_ERR(dwc->role_sw);
 
+	if (IS_ENABLED(CONFIG_OF)) {
+		/* populate connector entry */
+		int ret = devm_of_platform_populate(dwc->dev);
+
+		if (ret) {
+			usb_role_switch_unregister(dwc->role_sw);
+			dwc->role_sw = NULL;
+			dev_err(dwc->dev, "DWC3 platform devices creation failed: %i\n", ret);
+			return ret;
+		}
+	}
+
 	dwc3_set_mode(dwc, mode);
 	return 0;
 }