[media] go7007: fix invalid use of sizeof in go7007_usb_i2c_master_xfer()

sizeof() when applied to a pointer typed expression gives the
size of the pointer, not that of the pointed data.
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/staging/media/go7007/go7007-usb.c

@@ -1037,7 +1037,7 @@ static int go7007_usb_i2c_master_xfer(struct i2c_adapter *adapter,
 						buf, buf_len, 0) < 0)
 			goto i2c_done;
 		if (msgs[i].flags & I2C_M_RD) {
-			memset(buf, 0, sizeof(buf));
+			memset(buf, 0, msgs[i].len + 1);
 			if (go7007_usb_vendor_request(go, 0x25, 0, 0, buf,
 						msgs[i].len + 1, 1) < 0)
 				goto i2c_done;