Add support for the ASUS M2N-E board.

This is an AMD K8 + NVIDIA MCP55 + ITE IT8716F mainboard.

It has a working hda_verb.h file for HD audio, and a fanctl.c file is
used to enable the CPU fan (among others) so that we don't kill the
CPU due to excessive heat.

Even though some TODOs remain of course, it works good enough to
successfully boot Linux (e.g. via SeaBIOS).

The full status report is available at:
http://www.coreboot.org/ASUS_M2N-E

Signed-off-by: Uwe Hermann <uwe@hermann-uwe.de>
Acked-by: Peter Stuge <peter@stuge.se>
git-svn-id: svn://svn.coreboot.org/coreboot/trunk@6170 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1