linux-nilrt.inc: Remove headers from kernel-dev
linux-nilrt.inc: Remove headers from kernel-dev

The code we previously added to add kernel headers and build scripts
to kernel-dev package is not required because they are provided by
kernel-devsrc package.

Signed-off-by: Chaitanya Vadrevu <3811a3cb328197c46ad44d4be31bbd66ea52bfbb@ni.com>

ni/meta-nilrt,ni/meta-nilrt,ni/meta-nilrt,ni/meta-nilrt,ni/meta-nilrt