MIPS: VRX200: add support for ZyXEL P-2812HNU-Fx

The values in ddr_settings.h are (most likely) not correct. But at least one
can get to u-boot shell.

Signed-off-by: Luka Perkov <luka@openwrt.org>
MIPS: VRX200: add option to boot from factory ZTE loader

Signed-off-by: Luka Perkov <luka@openwrt.org>
MIPS: VRX200: add support for ZTE ZXHN H367N

Signed-off-by: Luka Perkov <luka@openwrt.org>
MIPS: lantiq: don't enable loads command by default

Signed-off-by: Luka Perkov <luka@openwrt.org>
MIPS: zyxel: update config for P-2601HN-Fx

Signed-off-by: Luka Perkov <luka@openwrt.org>

---
This should be "fixup"-ed with following commit:

31b55b4 MIPS: add board support for ZyXEL P-2601HN-Fx
MIPS: lantiq: fix SPL on ar9

Signed-off-by: Luka Perkov <luka@openwrt.org>