ARM: dts: i.MX51: digi-connectcore-som: Setup usbotg vbus-supply

The VBUS on usbotg is connected to the PMIC SWBST, let's reflect
that in the bindings.
Signed-off-by: Alexander Shiyan <eagle.alexander923@gmail.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm/boot/dts/imx51-digi-connectcore-som.dtsi

@@ -184,6 +184,7 @@ &nfc {
 &usbotg {
 	phy_type = "utmi_wide";
 	disable-over-current;
+	vbus-supply = <&swbst_reg>;
 	/* Device role is not known, keep status disabled */
 };