gma: Add flag to allow use of VGACNTRL on GMCH

Change-Id: If2f12f14b4f367cdfc8cc2c20402f2350e3bbba8
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/25404
Reviewed-by: Nico Huber <nico.h@gmx.de>
diff --git a/common/hw-gfx-gma-config.ads.template b/common/hw-gfx-gma-config.ads.template
index a8e89d3..2349272 100644
--- a/common/hw-gfx-gma-config.ads.template
+++ b/common/hw-gfx-gma-config.ads.template
@@ -56,6 +56,7 @@
    Has_DSP_Linoff          : constant Boolean := CPU <= Ivybridge;
    Has_PF_Pipe_Select      : constant Boolean := CPU in Ivybridge .. Haswell;
    VGA_Plane_Workaround    : constant Boolean := CPU = Ivybridge;
+   Has_GMCH_VGACNTRL       : constant Boolean := false;
 
    ----- Panel power: -----
    Has_PP_Write_Protection : constant Boolean := CPU <= Ivybridge;