Update add-db-to-osd.sh

Author: Hutch-45D

add-db-to-osd.sh

@@ -234,7 +234,7 @@ for i in "${!OSD_LIST[@]}"; do
     done
 
     OK_TO_STOP=$(ceph osd ok-to-stop $OSD_ID)
-    if [ $OK_TOP_STOP -ne 0 ]; then
+    if [[ $OK_TOP_STOP -ne 0 ]]; then
        echo "Error: stopping osd.$OSD_ID would result in data unavailability"
        exit 1
     fi