poky-lsb: Remove including security_flags.inc

This is in  default distro config now

(From meta-yocto rev: c85fa6a397d7ed97779ce347d4013cd1ea99d53f)

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta-poky/conf/distro/poky-lsb.conf

@@ -1,6 +1,5 @@
 
 require conf/distro/poky.conf
-require conf/distro/include/security_flags.inc
 
 DISTRO = "poky-lsb"
 DISTROOVERRIDES = "poky:linuxstdbase"