Update impermanence config

Signed-off-by: Nikolaos Karaolidis <nick@karaolidis.com>

hosts/common/configs/system/impermanence/scripts/wipe.sh

@@ -8,13 +8,8 @@ delete_subvolume_recursively() {
   btrfs subvolume delete "$1"
 }
 
-if [[ -z "$DEVICE" ]]; then
-  echo "Error: DEVICE variable is not set."
-  exit 1
-fi
-
 mkdir -p /mnt/btrfs
-mount "/dev/mapper/$DEVICE" /mnt/btrfs
+mount "$DEVICE" /mnt/btrfs
 
 if [[ -e /mnt/btrfs/@ ]]; then
   mkdir -p /mnt/btrfs/@.bak