[SCSI] megaraid: remove a spurious IRQ enable

We took this lock with spin_lock() so we should unlock it with
spin_unlock() instead of spin_unlock_irq().  This was introduced in
f2c8dc402b "[SCSI] megaraid_mbox: remove scsi_assign_lock usage".

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Adam Radford <aradford@gmail.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
diff --git a/drivers/scsi/megaraid/megaraid_mbox.c b/drivers/scsi/megaraid/megaraid_mbox.c
index 35bd138..54b1c5b 100644
--- a/drivers/scsi/megaraid/megaraid_mbox.c
+++ b/drivers/scsi/megaraid/megaraid_mbox.c
@@ -2731,7 +2731,7 @@
 	}
 
  out:
-	spin_unlock_irq(&adapter->lock);
+	spin_unlock(&adapter->lock);
 	return rval;
 }