scsi: qla2xxx: Utilize pci_alloc_irq_vectors/pci_free_irq_vectors calls.

Replaces the old pci_enable_msi[x]* and pci_disable_msi[x] calls.

Signed-off-by: Michael Hernandez <michael.hernandez@cavium.com>
Signed-off-by: Himanshu Madhani <himanshu.madhani@cavium.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>