Allow domains to getattr proc lnk_file.

Many permissions were removed from untrusted_app by the removal of
domain_deprecated, including procfs access. procfs file access was restored,
however, but not completely.  Add the ability to getattr to all domains,
so that other domains which lost domain_deprecated may benefit, as they
will likely need it.

Bug: 27249037
Change-Id: Id3f5e6121548b29d739d5e0fa6ccdbc9f0fc29be