mb/gigabyte/ga-945gcm-s2l: add mainboard

Startpoint was Intel d945gclf, which has same chipset and
Gigabyte ga-g41m-es2l which has same Superio.

What works and is tested:
* PCI slot;
* PCIe x16 slot with GPU (RADEON HD 2600 XT) and ADD2 DVI card;
* onboard VGA output (only textmode implemented) with native graphic init;
* 533, 800, 1067MHz FSB CPU (1333MHz is unsupported by the chipset);
* serial output during and after boot.

What does not work:
* resume from suspend (does not work for d945gclf either).

* The Realtek ethernet card requires a reset which currently also
  hardcodes a MAC adress.

This board was only tested with the SeaBIOS payload due to flash size
constraints (512KB) and with GNU/Linux.

Change-Id: I0ff9f193105facc1b276a791790e27eb4c275085
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/17033
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <martinroth@google.com>
diff --git a/src/mainboard/gigabyte/ga-945gcm-s2l/Makefile.inc b/src/mainboard/gigabyte/ga-945gcm-s2l/Makefile.inc
new file mode 100644
index 0000000..f9621db
--- /dev/null
+++ b/src/mainboard/gigabyte/ga-945gcm-s2l/Makefile.inc
@@ -0,0 +1 @@
+ramstage-y += cstates.c