Add fall through comments

Add comments to switch case construct.

lib/activate/dev_manager.c

@@ -1687,6 +1687,7 @@ static int _tree_action(struct dev_manager *dm, struct logical_volume *lv,
 		dm_tree_skip_lockfs(root);
 		if (!dm->flush_required && (lv->status & MIRRORED) && !(lv->status & PVMOVE))
 			dm_tree_use_no_flush_suspend(root);
+		/* Fall through */
 	case SUSPEND_WITH_LOCKFS:
 		if (!dm_tree_suspend_children(root, dlid, ID_LEN + sizeof(UUID_PREFIX) - 1))
 			goto_out;

lib/config/config.c

@@ -808,6 +808,7 @@ static void _get_token(struct parser *p, int tok_prev)
 
 	case '.':
 		p->t = TOK_FLOAT;
+		/* Fall through */
 	case '0':
 	case '1':
 	case '2':

lib/metadata/lv_manip.c

@@ -1512,6 +1512,7 @@ static int _find_some_parallel_space(struct alloc_handle *ah, const struct alloc
 
 				case PREFERRED:
 					preferred_count++;
+					/* Fall through */
 
 				case NEXT_PV:
 					goto next_pv;