unmount_device() use double quote when needed

init.sh

@@ -170,18 +170,19 @@ create_dir(){
 
 # unmount if device is mounted
 umount_device (){
-local mounted_part=$(mount | grep "${1}[0-9]" | awk '{print $3}')
-if [ !  "$mounted_part" == "" ]
-then
+    local mounted_part
+    mounted_part=$(mount | grep "${1}[0-9]" | awk '{print $3}')
+    if [ !  "$mounted_part" == "" ]
+    then
         for part  in $mounted_part
         do
-        if [ -d $part ]
+            if [ -d "$part" ]
             then
                 printf "Unmount %s\n " "$part"
-            umount $part --recursive
+                umount "$part" --recursive
             fi
         done
-fi
+    fi
 }
 
 efi_create_key_structure () {