added new seandroid rules

Allow GTP task to read shared rfs/tftp files
types of accessed granted to location domain:
    rfs_shared_hlos_file:dir r_dir_perms
    rfs_shared_hlos_file:file r_file_perms

CRs-fixed: 776909

Change-Id: Ib30e0f5b670e64e7ba533cad667ebe4f12cd8894