Shell needs to read /storage/self/primary symlink.

avc: denied { read } for name="primary" dev="tmpfs" ino=3134 scontext=u:r:shell:s0 tcontext=u:object_r:storage_file:s0 tclass=lnk_file

Change-Id: Id0ed2297a89054199fc73f27b18f717ae19c6778