smsc95xx: fix operation on 64-bit systems

smsc95xx_read_reg() should calculate sizeof(*data) not sizeof(data) since
data is a pointer, and the value pointed at is being transferred over USB,
not the value of the pointer. This fixes operation of the driver in 64-bit
builds, such as the Raspberry Pi 3.

Reported-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
Acked-by: Marek Vasut <marex@denx.de>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>

drivers/usb/eth/smsc95xx.c

@@ -188,10 +188,10 @@ static int smsc95xx_read_reg(struct usb_device *udev, u32 index, u32 *data)
 	len = usb_control_msg(udev, usb_rcvctrlpipe(udev, 0),
 			      USB_VENDOR_REQUEST_READ_REGISTER,
 			      USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
-			      0, index, tmpbuf, sizeof(data),
+			      0, index, tmpbuf, sizeof(*data),
 			      USB_CTRL_GET_TIMEOUT);
 	*data = tmpbuf[0];
-	if (len != sizeof(data)) {
+	if (len != sizeof(*data)) {
 		debug("smsc95xx_read_reg failed: index=%d, len=%d",
 		      index, len);
 		return -EIO;