x4x: add non documented vram sizes

The Intel documtentation, "Intel ® 4 Series Chipset Family"
mentions the possibility of 1, 4, 8 and 16M of preallocated
memory for the IGD, but does not document this.

This allows to set those undocumented values.
TESTED on ga-g41m-es2l with 2G dimm in one slot and 2x2G.

Change-Id: I92beb8d78907d4514a5aaf69248dd607dcf227c0
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/15491
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
diff --git a/src/northbridge/intel/x4x/raminit_ddr2.c b/src/northbridge/intel/x4x/raminit_ddr2.c
index 5d457e6..ed6ab60 100644
--- a/src/northbridge/intel/x4x/raminit_ddr2.c
+++ b/src/northbridge/intel/x4x/raminit_ddr2.c
@@ -1625,7 +1625,8 @@
 	u32 gfxsize, gttsize, tsegsize, mmiosize, tom, tolud, touud;
 	u32 gfxbase, gttbase, tsegbase, reclaimbase, reclaimlimit;
 	u16 ggc;
-	u16 ggc2uma[] = { 0, 0, 0, 0, 0, 32, 48, 64, 128, 256, 96, 160, 224, 352 };
+	u16 ggc2uma[] = { 0, 1, 4, 8, 16, 32, 48, 64, 128, 256, 96,
+			  160, 224, 352 };
 	u8 ggc2gtt[] = { 0, 1, 0, 2, 0, 0, 0, 0, 0, 2, 3, 4};
 
 	ggc = pci_read_config16(PCI_DEV(0,0,0), 0x52);