vxge: use pci_request_region()

Only BAR0 is ever accessed, thus making the calls to pci_request_regions
overkill.  Change calls of pci_request_regions to pci_request_region to
reduce the size of the mapped area.

Signed-off-by: Jon Mason <jon.mason@exar.com>
Signed-off-by: Ram Vepa <ram.vepa@exar.com>
Signed-off-by: David S. Miller <davem@davemloft.net>