gma hsw+: Revise Has_DDI_D flag

The GFX Programmer's Reference Manuals (PRMs) aren't clear on this but
it's pretty clear from the processor datasheets which SKUs expose which
pins: All U/Y processors lack DDI D.

Change-Id: I84c40b6bc01091de8a512e21354243c74643e0f5
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/20820
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
diff --git a/common/hw-gfx-gma-config.ads.template b/common/hw-gfx-gma-config.ads.template
index e82b133..3f7ca64 100644
--- a/common/hw-gfx-gma-config.ads.template
+++ b/common/hw-gfx-gma-config.ads.template
@@ -91,9 +91,11 @@
                                                   and CPU_Var = ULT) or
                                                  CPU >= Skylake;
 
-   Has_DDI_D               : constant Boolean := (CPU in Haswell .. Broadwell
-                                                  and CPU_Var = Normal)
-                                                 or CPU >= Skylake;
+   Has_DDI_PHYs            : constant Boolean := CPU = Broxton;
+
+   Has_DDI_D               : constant Boolean := CPU >= Haswell and
+                                                 CPU_Var = Normal and
+                                                 not Has_DDI_PHYs;
 
    Has_DDI_Buffer_Trans    : constant Boolean := CPU >= Haswell and
                                                  CPU /= Broxton;
@@ -102,8 +104,6 @@
 
    Need_DP_Aux_Mutex       : constant Boolean := False; -- Skylake & (PSR | GTC)
 
-   Has_DDI_PHYs            : constant Boolean := CPU = Broxton;
-
    ----- GMBUS: -----------
    Ungate_GMBUS_Unit_Level : constant Boolean := CPU >= Skylake;
    GMBUS_Alternative_Pins  : constant Boolean := CPU = Broxton;