can: janz-ican3: initialize dlc variable

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: b01d5543f78d ("can: do not increase tx_bytes statistics for RTR frames")
Link: https://lore.kernel.org/all/20220108143319.3986923-1-trix@redhat.com
Signed-off-by: Tom Rix <trix@redhat.com>
Acked-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>