kernel : added IPV6 NAT support in defconfig

This changes will help to install V6 NAT tables.

Acked-by: Utkal shah <c_ushah@qti.qualcomm.com>
Change-Id: I1e28e1653b9f4602d385e543777434f6a375775e
Signed-off-by: Aman Gupta <amangupt@codeaurora.org>