pch_can: fix rmmod issue

Currently, when rmmod pch_can, kernel failure occurs.
The cause is pci_iounmap executed before pch_can_reset.
Thus pci_iounmap moves after pch_can_reset.

Signed-off-by: Tomoya MORINAGA <tomoya-linux@dsn.okisemi.com>
Signed-off-by: David S. Miller <davem@davemloft.net>