defconfig: Enable SELinux and its dependencies

To have more control over the access rights for different
user space needs, SELinux imposes mandatory access controls
on Linux. Which allows an administrator of a system to
define how applications and users can access different
resources such as files, devices, networks and inter-process
communication.

Change-Id: Ib01664c8a5b64a7f4aac6378e4ddaf27d80ac1e2
Signed-off-by: Satya Durga Srinivasu Prabhala <satyap@codeaurora.org>