This is already fixed in the master branch (currently unreleased)

commit ca762806fd6b5b455c42ef85833ff92c791eabe8
Author: Juergen Hoetzel <juergen@archlinux.org>
Date:   Fri Aug 7 18:00:00 2015 +0200

    * tramp-adb.el (tramp-adb-ls-output-name-less-p): Improve error
      checking. "ls -l" on Android in Enforcing mode can print "lstat
      './FILENAME failed: Permission denied".