restorecon_recursive /cache

Make sure all files / directories within /cache are properly
labeled, not just the directory itself.

Addresses the following denial:

  type=1400 audit(0.0:26): avc: denied { getattr } for comm="Thread-85" path="/cache/lost+found" dev="mmcblk0p27" ino=11 scontext=u:r:untrusted_app:s0 tcontext=u:object_r:unlabeled:s0 tclass=dir

Change-Id: I5937b30043efeb696ffaa77258b7294d20d1494e