usb: chipidea: pull down dp for possible charger detection operation

The bootloader may use device mode, and keep dp up. We need dp
to be pulled down before possbile charger detection operation.

Signed-off-by: Peter Chen <peter.chen@nxp.com>

drivers/usb/chipidea/core.c

@@ -1123,8 +1123,11 @@ static int ci_hdrc_probe(struct platform_device *pdev)
 
 	if (!ci_otg_is_fsm_mode(ci)) {
 		/* only update vbus status for peripheral */
-		if (ci->role == CI_ROLE_GADGET)
+		if (ci->role == CI_ROLE_GADGET) {
+			/* Pull down DP for possible charger detection */
+			hw_write(ci, OP_USBCMD, USBCMD_RS, 0);
 			ci_handle_vbus_change(ci);
+		}
 
 		ret = ci_role_start(ci, ci->role);
 		if (ret) {