cpqarray: enable bus mastering

We've been carrying this patch for the last 3 years in Fedora,
long past time we got it upstream...

Call pci_set_master to enable bus-mastering if the BIOS hasn't
done it already.

Signed-off-by: Kyle McMartin <kyle@redhat.com>
Signed-off-by: Dave Jones <davej@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>