[scripts] automatic kernel upgrade: remove empty directory only when it's empty

scripts/inner_source_chroot_update.sh

@@ -57,9 +57,9 @@ if [ "${current_kernel}" != "${available_kernel}" ] && \
 			paren_children=$(find "${paren_slink}")
 			if [ -z "${paren_children}" ]; then
 				echo "${paren_slink} is empty, removing"
-			fi
 				rmdir "${paren_slink}" # ignore failure, best effort
 			fi
+		fi
 	done
 else
 	echo "@@ Not upgrading kernels:"