gma: Add flag to use GMCH GMBUS registers

Change-Id: Id5d115c7a4711f634171e6e163439ebab4ee6076
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/25405
Reviewed-by: Nico Huber <nico.h@gmx.de>
diff --git a/common/hw-gfx-gma-registers.ads b/common/hw-gfx-gma-registers.ads
index 1515fab..37e62e8 100644
--- a/common/hw-gfx-gma-registers.ads
+++ b/common/hw-gfx-gma-registers.ads
@@ -44,6 +44,12 @@
       ARB_MODE,
       HWS_PGA,
       GAM_ECOCHK,
+      GMCH_GMBUS0,
+      GMCH_GMBUS1,
+      GMCH_GMBUS2,
+      GMCH_GMBUS3,
+      GMCH_GMBUS4,
+      GMCH_GMBUS5,
       MBCTL,
       UCGCTL1,
       UCGCTL2,
@@ -1347,6 +1353,12 @@
       SDEIER                => 16#0c_400c# / Register_Width,
 
       -- I2C stuff
+      GMCH_GMBUS0           => 16#00_5100# / Register_Width,
+      GMCH_GMBUS1           => 16#00_5104# / Register_Width,
+      GMCH_GMBUS2           => 16#00_5108# / Register_Width,
+      GMCH_GMBUS3           => 16#00_510c# / Register_Width,
+      GMCH_GMBUS4           => 16#00_5110# / Register_Width,
+      GMCH_GMBUS5           => 16#00_5120# / Register_Width,
       PCH_GMBUS0            => 16#0c_5100# / Register_Width,
       PCH_GMBUS1            => 16#0c_5104# / Register_Width,
       PCH_GMBUS2            => 16#0c_5108# / Register_Width,