can: vxcan: vxcan_xmit(): use kfree_skb() instead of kfree() to free skb

This patch fixes the freeing of the "oskb", by using kfree_skb()
instead of kfree().

Fixes: 1574481b ("vxcan: remove sk reference in peer skb")
Link: https://lore.kernel.org/all/20220311123741.382618-1-mkl@pengutronix.de


Cc: Oliver Hartkopp <socketcan@hartkopp.net>
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>