can: janz-ican3: initialize dlc variable

Clang static analysis reports this problem
janz-ican3.c:1311:2: warning: Undefined or garbage value returned to caller
        return dlc;
        ^~~~~~~~~~

dlc is only set with this conditional
	if (!(cf->can_id & CAN_RTR_FLAG))
		dlc = cf->len;

But is always returned.  So initialize dlc to 0.

Fixes: cc4b08c3 ("can: do not increase tx_bytes statistics for RTR frames")
Link: https://lore.kernel.org/all/20220108143319.3986923-1-trix@redhat.comSigned-off-by: Tom Rix <trix@redhat.com>
Acked-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/janz-ican3.c

@@ -1285,7 +1285,7 @@ static unsigned int ican3_get_echo_skb(struct ican3_dev *mod)
 {
 	struct sk_buff *skb = skb_dequeue(&mod->echoq);
 	struct can_frame *cf;
-	u8 dlc;
+	u8 dlc = 0;
 
 	/* this should never trigger unless there is a driver bug */
 	if (!skb) {