scsi: dpt_i2o: Drop redundant spinlock initialization

adpt_post_wait_lock was declared and initialized by DEFINE_SPINLOCK so we
don't need to call spin_lock_init(). Drop the call.

Link: https://lore.kernel.org/r/1652176024-3981-1-git-send-email-baihaowen@meizu.com
Signed-off-by: Haowen Bai <baihaowen@meizu.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>