gma: Show that we never try to downscale the image

This helps to simplify follow-up code that enables scaling.

Change-Id: I2796117e00249aa6654d627eee51ffdb37016d8b
Signed-off-by: Nico Huber <nico.huber@secunet.com>
Reviewed-on: https://review.coreboot.org/17262
Tested-by: Nico Huber <nico.h@gmx.de>
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
diff --git a/common/hw-gfx-gma-connector_info.ads b/common/hw-gfx-gma-connector_info.ads
index 0de8ba0..171b558 100644
--- a/common/hw-gfx-gma-connector_info.ads
+++ b/common/hw-gfx-gma-connector_info.ads
@@ -26,14 +26,18 @@
    procedure Preferred_Link_Setting
      (Port_Cfg : in out Port_Config;
       Success  :    out Boolean)
-      with
-         Post => (Port_Cfg.Port = Port_Cfg.Port'Old);
+   with
+      Post =>
+         Port_Cfg.Port = Port_Cfg.Port'Old and
+         Port_Cfg.Mode = Port_Cfg.Mode'Old;
 
    procedure Next_Link_Setting
      (Port_Cfg : in out Port_Config;
       Success  :    out Boolean)
-      with
-         Post => (Port_Cfg.Port = Port_Cfg.Port'Old);
+   with
+      Post =>
+         Port_Cfg.Port = Port_Cfg.Port'Old and
+         Port_Cfg.Mode = Port_Cfg.Mode'Old;
 
    function Default_BPC (Port_Cfg : Port_Config) return BPC_Type;