be2net: re-factor bar mapping code

1) separate NIC and roce bar mapping code
2) parse sli_intf::if_type inside be_map_pci_bars() as if_type must be
   used only to identify bars.
3) Use pci_iomap/unmap() routines

Signed-off-by: Sathya Perla <sathya.perla@emulex.com>
Signed-off-by: David S. Miller <davem@davemloft.net>