mb/gigabyte/ga-b75m-d3h: add libgfxinit support

Currently native video init works on port HDMI1 (wired to the
on-board DVI-D socket) , HDMI3 (the on-board HDMI port), and the VGA
port, both text mode and fb mode.

Every ports works on GNU/Linux.

Tested against an IVB cpu (i7-3770T).

Change-Id: If00a7247df0c32b3d1f489fb92d86baaa8fdf8ba
Signed-off-by: Bill XIE <persmule@gmail.com>
Reviewed-on: https://review.coreboot.org/19522
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>

src/mainboard/gigabyte/ga-b75m-d3h/Kconfig

@@ -17,6 +17,7 @@ config BOARD_SPECIFIC_OPTIONS
 	select INTEL_INT15
 	select UDELAY_TSC
 	select SERIRQ_CONTINUOUS_MODE
+	select MAINBOARD_HAS_LIBGFXINIT
 
 config MMCONF_BASE_ADDRESS
 	hex

src/mainboard/gigabyte/ga-b75m-d3h/Makefile.inc

@@ -14,3 +14,4 @@
 ##
 
 romstage-y += gpio.c
+ramstage-$(CONFIG_MAINBOARD_USE_LIBGFXINIT) += gma-mainboard.ads

src/mainboard/gigabyte/ga-b75m-d3h/gma-mainboard.ads

@@ -0,0 +1,15 @@
+with HW.GFX.GMA;
+with HW.GFX.GMA.Display_Probing;
+
+use HW.GFX.GMA;
+use HW.GFX.GMA.Display_Probing;
+
+private package GMA.Mainboard is
+
+   ports : constant Port_List :=
+     (HDMI1,
+      HDMI3,
+      Analog,
+      others => Disabled);
+
+end GMA.Mainboard;