scsi: fnic: Fix missed link-up when critical IRQ targets offline CPU

When CPU Hyper Threading is disabled, sibling CPUs remain present but
are reported offline. Managed MSI-X IRQs can still receive affinity
masks that include those offline CPUs. If a driver-critical vector is
managed, it can be parked on an offline CPU and the driver may miss
critical events such as link-up.

Keep driver-critical vectors unmanaged so they can be migrated by the
IRQ core when their target CPU is offlined.

Since HWQ-0 is unmanaged now, in some queue combinations there can be no
mappings to it in mq_map. So without the blk-mq fix mentioned below,
system may crash during cpu offline/online tests.

Fixes: 8a8449ca5e33 ("scsi: fnic: Modify ISRs to support multiqueue (MQ)")
Cc: stable@vger.kernel.org
Depends-on: commit 10845a105bbc ("blk-mq: skip CPU offline notify on unmapped hctx")
Reviewed-by: Sesidhar Baddela <sebaddel@cisco.com>
Reviewed-by: Arulprabhu Ponnusamy <arulponn@cisco.com>
Reviewed-by: Gian Carlo Boffa <gcboffa@cisco.com>
Reviewed-by: Karan Tilak Kumar <kartilak@cisco.com>
Signed-off-by: Arun Easi <aeasi@cisco.com>
Reviewed-by: Laurence Oberman <loberman@redhat.com>
Link: https://patch.msgid.link/20260903175547.57971-1-aeasi@cisco.com
Signed-off-by: Martin K. Petersen (Oracle) <mkp@kernel.org>

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