gma config: Introduce Have_HDMI_Buf_Override

Change-Id: Id00ae200cc8d08ce245d57b2886a40f0fea10167
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/c/libgfxinit/+/27049
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
diff --git a/common/hw-gfx-gma-config.ads.template b/common/hw-gfx-gma-config.ads.template
index 150937d..398b340 100644
--- a/common/hw-gfx-gma-config.ads.template
+++ b/common/hw-gfx-gma-config.ads.template
@@ -35,6 +35,7 @@
 
    ----------------------------------------------------------------------------
 
+   Have_HDMI_Buf_Override  : constant Boolean := DDI_HDMI_Buffer_Translation >= 0;
    Default_MMIO_Base_Set   : constant Boolean := Default_MMIO_Base /= 0;
 
    Has_Internal_Display    : constant Boolean := Internal_Display /= None;