cnic: Don't use netdev->base_addr

commit c0357e97
    bnx2: stop using net_device.{base_addr, irq}.

removed netdev->base_addr so we need to update cnic to get the MMIO
base address from pci_resource_start().  Otherwise, mmap of the uio
device will fail.

Signed-off-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>