We need to check the address that pci_alloc_consistent() returns since
it might fail.

When pci_alloc_consistent() fails, some IOMMUs set the dma_handle
argument to zero. So we can't use fibptr->hw_fib_pa directly here.
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: Aacraid List <aacraid@adaptec.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>