scsi: fnic: Make fnic_queuecommand() easier to analyze

Move a spin_unlock_irqrestore() call such that the io_lock_acquired
variable can be eliminated. This patch prepares for enabling the Clang
thread-safety analyzer.

Cc: Satish Kharat <satishkh@cisco.com>
Cc: Sesidhar Baddela <sebaddel@cisco.com>
Cc: Karan Tilak Kumar <kartilak@cisco.com>
Cc: James E.J. Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Cc: linux-scsi@vger.kernel.org
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Karan Tilak Kumar <kartilak@cisco.com>
Link: https://patch.msgid.link/20260223220102.2158611-30-bart.vanassche@linux.dev
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>