pch_can: depends on PCI

Fix pch_can build when CONFIG_PCI is not enabled.  It uses pci interfaces
and data structures, so it should depend on PCI.

drivers/net/can/pch_can.c:1044: error: implicit declaration of function 'pci_enable_msi'
drivers/net/can/pch_can.c:1079: error: implicit declaration of function 'pci_disable_msi'

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>