phy: rockchip-inno-usb2: add a delay after phy resume

When resume phy, it need about 1.5 ~ 2ms to wait for
utmi_clk which used for USB controller to become stable.

Change-Id: I319a28069b4b3381f22cc34567226f341e948bd4
Signed-off-by: William Wu <william.wu@rock-chips.com>

drivers/phy/phy-rockchip-inno-usb2.c

@@ -534,6 +534,9 @@ static int rockchip_usb2phy_power_on(struct phy *phy)
 	if (ret)
 		return ret;
 
+	/* waiting for the utmi_clk to become stable */
+	usleep_range(1500, 2000);
+
 	rport->suspended = false;
 	return 0;
 }