V4L/DVB (8829): gspca: Have a clean kmalloc-ated buffer for USB exchanges.

The USB buffer may be used for DMA and there may be a caching problem
if the buffer is part of the device structure.
Thanks to Alan Stern.

Signed-off-by: Jean-Francois Moine <moinejf@free.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/drivers/media/video/gspca/etoms.c b/drivers/media/video/gspca/etoms.c
index c03b1f4..9eb6adb 100644
--- a/drivers/media/video/gspca/etoms.c
+++ b/drivers/media/video/gspca/etoms.c
@@ -235,7 +235,7 @@
 	struct usb_device *dev = gspca_dev->dev;
 
 #ifdef GSPCA_DEBUG
-	if (len > sizeof gspca_dev->usb_buf) {
+	if (len > USB_BUF_SZ) {
 		err("reg_r: buffer overflow");
 		return;
 	}
@@ -273,7 +273,7 @@
 	struct usb_device *dev = gspca_dev->dev;
 
 #ifdef GSPCA_DEBUG
-	if (len > sizeof gspca_dev->usb_buf) {
+	if (len > USB_BUF_SZ) {
 		err("reg_w: buffer overflow");
 		return;
 	}