sepolicy: Add macro for libsoc helper module

Adds permissions needed for vendor modules to
get soc info at run time. All native clients
using the libsoc helper module must use
the macro for their domain.

The existing permission needs are empty
(already part of domain) but added placeholder
to allow any underlying mechanism changes that
may require new permissions.

Change-Id: Iaeb93c5473f03c7b3b7956e8bbb5ec6ed733ae4f