adbd: allow "adb pull /sdcard/"

The removal of domain_deprecated broke the ability for adbd to
pull files from /sdcard. Re-allow it.

Addresses the following denials:

  avc: denied { search } for pid=2753 comm=73657276696365203530 name="/" dev="tmpfs" ino=6242 scontext=u:r:adbd:s0 tcontext=u:object_r:tmpfs:s0 tclass=dir permissive=0
  avc: denied { getattr } for pid=2755 comm=73657276696365203431 path="/sdcard" dev="rootfs" ino=5472 scontext=u:r:adbd:s0 tcontext=u:object_r:rootfs:s0 tclass=lnk_file permissive=0

Change-Id: I70257933f554abd008932c7f122dd0151f464b05