scsi: qla2xxx: Fix NULL pointer dereference in target mode

scsi: qla2xxx: Fix NULL pointer dereference in target mode

When target mode is enabled, the pci_irq_get_affinity() function may return
a NULL value in qla_mapq_init_qp_cpu_map() due to the qla24xx_enable_msix()
code that handles IRQ settings for target mode. This leads to a crash due
to a NULL pointer dereference.

This patch fixes the issue by adding a check for the NULL value returned by
pci_irq_get_affinity() and introducing a 'cpu_mapped' boolean flag to the
qla_qpair structure, ensuring that the qpair's CPU affinity is updated when
it has not been mapped to a CPU.

Fixes: 1d201c81d4cc ("scsi: qla2xxx: Select qpair depending on which CPU post_cmd() gets called")
Signed-off-by: Gleb Chesnokov <gleb.chesnokov@scst.dev>
Link: https://lore.kernel.org/r/56b416f2-4e0f-b6cf-d6d5-b7c372e3c6a2@scst.dev
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>