scsi: mpi3mr: Fix race between config read submit and interrupt completion

scsi: mpi3mr: Fix race between config read submit and interrupt completion

The "is_waiting" flag was updated after calling complete(), which could
lead to a race where the waiting thread wakes up before the flag is
cleared. This may cause a missed wakeup or stale state check.

Reorder the operations to update "is_waiting" before signaling completion
to ensure consistent state.

Fixes: 824a156633df ("scsi: mpi3mr: Base driver code")
Cc: stable@vger.kernel.org
Co-developed-by: Chandrakanth Patil <chandrakanth.patil@broadcom.com>
Signed-off-by: Chandrakanth Patil <chandrakanth.patil@broadcom.com>
Signed-off-by: Ranjan Kumar <ranjan.kumar@broadcom.com>
Link: https://lore.kernel.org/r/20250627194539.48851-2-ranjan.kumar@broadcom.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>