Restructure sepolicy for EVS stack

Move EVS policies into their own folder so they can be selectively
included for platforms that need/want them.
Adopt hal_server_domain and hal_client_domain macros
Add comments to clarify intent

Test: boot and run on gordon_peak
Change-Id: I092d1251868dea9af7840ddfe75f98841e98fe37
13 files changed