scsi: mpt3sas: Free diag buffer without any status check

Memory leak can happen when diag buffer is released but not unregistered
(where buffer is deallocated) by the user. During module unload time driver
is not deallocating the buffer if the buffer is in released state.

Deallocate the diag buffer during module unload time without any diag
buffer status checks.

Link: https://lore.kernel.org/r/1568379890-18347-5-git-send-email-sreekanth.reddy@broadcom.com


Signed-off-by: Sreekanth Reddy <sreekanth.reddy@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>