org-mobile.el (org-mobile-create-index-file): Use `files-alist'.

* org-mobile.el (org-mobile-create-index-file): Use `files-alist'.

lisp/org-mobile.el

@@ -424,7 +424,7 @@ agenda view showing the flagged items."
 		     done-kwds
 		     (org-uniquify org-todo-keywords-for-agenda)))
     (setq drawers (org-uniquify org-drawers-for-agenda))
-    (setq tags (mapcar 'car (org-global-tags-completion-table org-mobile-files-alist)))
+    (setq tags (mapcar 'car (org-global-tags-completion-table files-alist)))
     (with-temp-file
 	(if org-mobile-use-encryption
 	    org-mobile-encryption-tempfile