s5p4418: friendlyarm nanopi2: add support

[pm.stefan]

Hello,

I just finished the migration of the friendlyARM U-Boot from
https://github.com/friendlyarm/u-boot/tree/nanopi2-v2016.01 (for boards
with s5p4418 SoC) to the current (official) U-Boot version because of a
private project. For v2016.01 I have also made a working SPL
(FriendlyARM U-Boot is using a closed source 2nd-bootloader). My plan is
to migrate this also to the current U-Boot.

Now, I need a value for "#define MACH_TYPE_S5P4418" in
arch/arm/include/asm/mach-types.h.

After this I will send the appropriate patches.

Regards,
Stefan