scsi: mpt3sas: fix an out of bound write

scsi: mpt3sas: fix an out of bound write

cpu_msix_table is allocated to store online cpus, but pci_irq_get_affinity
may return cpu_possible_mask which is then used to access cpu_msix_table.
That causes bad user experience.  Fix limits access to only online cpus,
I've also added an additional test to protect from an unlikely change in
cpu_online_mask.

[mkp: checkpatch]

Fixes: 1d55abc0e98a ("scsi: mpt3sas: switch to pci_alloc_irq_vectors")
Signed-off-by: Tomas Henzl <thenzl@redhat.com>
Acked-by: Suganath Prabu Subramani <suganath-prabu.subramani@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>