mfd: viperboard: Do version query in dma memory

The query for the viperboard version was done with memory buffer
on the stack but usb transfers need dma capable memory buffer.
This is fixed now.
Signed-off-by: NLars Poeschel <poeschel@lemonage.de>
Signed-off-by: NSamuel Ortiz <sameo@linux.intel.com>

drivers/mfd/viperboard.c

@@ -56,7 +56,6 @@ static int vprbrd_probe(struct usb_interface *interface,
 
 	u16 version = 0;
 	int pipe, ret;
-	unsigned char buf[1];
 
 	/* allocate memory for our device state and initialize it */
 	vb = kzalloc(sizeof(*vb), GFP_KERNEL);
@@ -76,17 +75,17 @@ static int vprbrd_probe(struct usb_interface *interface,
 	/* get version information, major first, minor then */
 	pipe = usb_rcvctrlpipe(vb->usb_dev, 0);
 	ret = usb_control_msg(vb->usb_dev, pipe, VPRBRD_USB_REQUEST_MAJOR,
-		VPRBRD_USB_TYPE_IN, 0x0000, 0x0000, buf, 1,
+		VPRBRD_USB_TYPE_IN, 0x0000, 0x0000, vb->buf, 1,
 		VPRBRD_USB_TIMEOUT_MS);
 	if (ret == 1)
-		version = buf[0];
+		version = vb->buf[0];
 
 	ret = usb_control_msg(vb->usb_dev, pipe, VPRBRD_USB_REQUEST_MINOR,
-		VPRBRD_USB_TYPE_IN, 0x0000, 0x0000, buf, 1,
+		VPRBRD_USB_TYPE_IN, 0x0000, 0x0000, vb->buf, 1,
 		VPRBRD_USB_TIMEOUT_MS);
 	if (ret == 1) {
 		version <<= 8;
-		version = version | buf[0];
+		version = version | vb->buf[0];
 	}
 
 	dev_info(&interface->dev,