[][Add Dual-PPE Support for NF_HNAT]

[Description]
Add NETSYS V2 Dual-PPE Support for NF_HNAT in order
to achieve peak throughput requirement.

If want to enable dual-ppe mode, just modify dts node
as follows:

	&hnat {
		... ...
	+	mtketh-ppe-num = <2>;
		... ...
	};

[Release-log]
N/A

Change-Id: Ibf6316f69592ad76aac2e5e36dac907127e23103
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/4526946
7 files changed