usb: gadget: lpc32xx_udc: Fix compatibility with STOTG04

The STOTG04 is an replacement for ISP1301.

Most of the registers on STOTG04 are the same as on ISP1301, but the
register ISP1301_I2C_OTG_CONTROL_2 (address 0x10) doesn't exist on the
ST part.

This is a work around for this by using the interrupt source register that
should behave the same on both parts and has the needed information.
Tested-by: Roland Stigge <stigge@antcom.de>
Signed-off-by: Alexandre Pereira da Silva <aletes.xgr@gmail.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/gadget/lpc32xx_udc.c

@@ -2930,10 +2930,10 @@ static void vbus_work(struct work_struct *work)
 
 		/* Get the VBUS status from the transceiver */
 		value = i2c_smbus_read_byte_data(udc->isp1301_i2c_client,
-						 ISP1301_I2C_OTG_CONTROL_2);
+						 ISP1301_I2C_INTERRUPT_SOURCE);
 
 		/* VBUS on or off? */
-		if (value & OTG_B_SESS_VLD)
+		if (value & INT_SESS_VLD)
 			udc->vbus = 1;
 		else
 			udc->vbus = 0;