scsi: fnic: switch to pci_alloc_irq_vectors

Not a full cleanup for the IRQ code, for that we'd need to know if the
max number of the various CQ types is going to stay 1 forever.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Satish Kharat <satishkh@cisco.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>