latona: Add basic SELinux policies

- Added basic sepolicy to allow device to boot (there's a bug that
  crashes the device without it)
- Added other sepolicies to fix denial and tighten processes
- Uses bind mount instead of symlink because file_contexts uses real
  path

  Ported basic SELinux policies from aries-common, adapted for latona board.
  TODO: Fix the policies for latona. Add permissions for the rest of devices (camera, gps, etc).

Change-Id: I0c518e780c79d2ed38838f90b7ad30fa29e3b55c
Signed-off-by: David Rodero <david@codiguiel.net>
latona: use selinux defconfig.

Change-Id: I7c41a2ce0880d92605c7cde618c8c7ebee8e4f7d
Signed-off-by: David Rodero <david@codiguiel.net>
latona: use LEGACY_EGL flag.

Change-Id: Idc82b5406b66bb19b80c6fa17230f02bad4057a0
Signed-off-by: David Rodero <david@codiguiel.net>