Only create the mount directory if it doesn't exist

src/freedombone

   echo 'fi' >> /usr/bin/$BACKUP_SCRIPT_NAME
   echo '' >> /usr/bin/$BACKUP_SCRIPT_NAME
   echo "umount -f $USB_MOUNT" >> /usr/bin/$BACKUP_SCRIPT_NAME
-  echo "mkdir $USB_MOUNT" >> /usr/bin/$BACKUP_SCRIPT_NAME
+  echo "if [ ! -d $USB_MOUNT ]; then" >> /usr/bin/$BACKUP_SCRIPT_NAME
+  echo "  mkdir $USB_MOUNT" >> /usr/bin/$BACKUP_SCRIPT_NAME
+  echo 'fi' >> /usr/bin/$BACKUP_SCRIPT_NAME
   echo 'if [ -f /dev/mapper/encrypted_usb ]; then' >> /usr/bin/$BACKUP_SCRIPT_NAME
   echo '  rm -rf /dev/mapper/encrypted_usb' >> /usr/bin/$BACKUP_SCRIPT_NAME
   echo 'fi' >> /usr/bin/$BACKUP_SCRIPT_NAME