defconfig: fsm9900: Move Netfilter/iptables components into modules

Netfilter has overhead and affects Ethernet performance. Fsm9900
configurations that require these features may load them at runtime.

Change-Id: Ibb7fffe732952184579fe84ef9c92d18c2eeb339
Acked-by: Kaushik Sikdar <ksikdar@qti.qualcomm.com>
Signed-off-by: Rohit Vaswani <rvaswani@codeaurora.org>