scsi: mpi3mr: Synchronize access to ioctl data buffer

scsi: mpi3mr: Synchronize access to ioctl data buffer

The driver serializes ioctls through a mutex lock but access to the
ioctl data buffer is not guarded by the mutex. This results in multiple
user threads being able to write to the driver's ioctl buffer
simultaneously.

Protect the ioctl buffer with the ioctl mutex.

Signed-off-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Ranjan Kumar <ranjan.kumar@broadcom.com>
Link: https://lore.kernel.org/r/20241110194405.10108-2-ranjan.kumar@broadcom.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>