1.Fix the invalid value about selinux policy
2.Update description of task about selinux.The permissive mode
need enable selinux.The parameter named "disable_selinux" is not good.
In order to customize selinux modes, we need a new
parameter named "selinux_state".

Closes-Bug: #1749046
Change-Id: I20c084cf2e46cc0de149afbd34c6dcb77a1051f4