can: sja1000: fix use after free in ems_pcmcia_add_card()

commit 3ec6ca6b upstream.

If the last channel is not available then "dev" is freed.  Fortunately,
we can just use "pdev->irq" instead.

Also we should check if at least one channel was set up.

Fixes: fd734c6f ("can/sja1000: add driver for EMS PCMCIA card")
Link: https://lore.kernel.org/all/20211124145041.GB13656@kili


Cc: stable@vger.kernel.org
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Oliver Hartkopp <socketcan@hartkopp.net>
Tested-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>