aac_fib_map_free() calls pci_free_consistent() without checking that
dev->hw_fib_va is not NULL and dev->max_fib_size is not zero.If they are
indeed NULL/0, this will result in a hang as pci_free_consistent() will
attempt to invalidate cache for the entire 64-bit address space
(which would take a very long time).

Fixed by adding a check to make sure that dev->hw_fib_va and
dev->max_fib_size are not NULL and 0 respectively.

Fixes: 9ad5204d - "[SCSI]aacraid: incorrect dma mapping mask during blinked recover or user initiated reset"
Cc: stable@vger.kernel.org
Signed-off-by: Raghava Aditya Renukunta <raghavaaditya.renukunta@pmcs.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Tomas Henzl <thenzl@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>