scsi: myrs: Fix uninitialized variable

drivers/scsi/myrs.c: In function 'myrs_log_event':
drivers/scsi/myrs.c:821:24: warning: 'sshdr.sense_key' may be used uninitialized in this function [-Wmaybe-uninitialized]
  struct scsi_sense_hdr sshdr;

If ev->ev_code is not 0x1C, sshdr.sense_key may be used uninitialized. Fix
this by initializing variable 'sshdr' to 0.

Fixes: 77266186

 ("scsi: myrs: Add Mylex RAID controller (SCSI interface)")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>