[media] gspca - sonixj: Fix a zero divide in isoc interrupt

In case of short marker, the number of received packets was not
incremented doing a zero divide when computing the filling rate.
Reported-by: Hans Petter Selasky <hans.petter.selasky@bitfrost.no>
Signed-off-by: Jean-François Moine <moinejf@free.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/gspca/sonixj.c

@@ -2923,6 +2923,10 @@ static void sd_pkt_scan(struct gspca_dev *gspca_dev,
 	 * not the JPEG end of frame ('ff d9').
 	 */
 
+	/* count the packets and their size */
+	sd->npkt++;
+	sd->pktsz += len;
+
 /*fixme: assumption about the following code:
  *	- there can be only one marker in a packet
  */
@@ -2945,10 +2949,6 @@ static void sd_pkt_scan(struct gspca_dev *gspca_dev,
 		data += i;
 	}
 
-	/* count the packets and their size */
-	sd->npkt++;
-	sd->pktsz += len;
-
 	/* search backwards if there is a marker in the packet */
 	for (i = len - 1; --i >= 0; ) {
 		if (data[i] != 0xff) {