scsi: qla2xxx: Zero undefined mailbox IN registers

While requesting a new mailbox command, driver does not write any data to
unused registers.  Initialize the unused register value to zero while
requesting a new mailbox command to prevent stale entry access by firmware.

Link: https://lore.kernel.org/r/20220713052045.10683-4-njavali@marvell.com


Cc: stable@vger.kernel.org
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: Bikash Hazarika <bhazarika@marvell.com>
Signed-off-by: Quinn Tran <qutran@marvell.com>
Signed-off-by: Nilesh Javali <njavali@marvell.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>