scsi: mpi3mr: Fix missing mrioc->evtack_cmds initialization

Commit c1af985d ("scsi: mpi3mr: Add Event acknowledgment logic")
introduced an array mrioc->evtack_cmds but initialization of the array
elements was missed. They are just zero cleared. The function
mpi3mr_complete_evt_ack() refers host_tag field of the elements. Due to the
zero value of the host_tag field, the function calls clear_bit() for
mrico->evtack_cmds_bitmap with wrong bit index. This results in memory
access to invalid address and "BUG: KASAN: use-after-free". This BUG was
observed at eHBA-9600 firmware update to version 8.3.1.0. To fix it, add
the missing initialization of mrioc->evtack_cmds.

Link: https://lore.kernel.org/r/20230214005019.1897251-5-shinichiro.kawasaki@wdc.com
Cc: stable@vger.kernel.org
Fixes: c1af985d

 ("scsi: mpi3mr: Add Event acknowledgment logic")
Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Acked-by: Sathya Prakash Veerichetty <sathya.prakash@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>