gma config_helpers: Pass only the modeline to Validate_Config()

Validate_Config() had the full `Port_Config` as parameter, though we
only accessed the modeline. Make that explicit so we can also call it
when we don't have the full config available.

Change-Id: Ia4620d1ffa1a3cd098d721d84f2453f2dc19da2a
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/23163
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
diff --git a/common/hw-gfx-gma-config_helpers.ads b/common/hw-gfx-gma-config_helpers.ads
index 1dc2390..4853634 100644
--- a/common/hw-gfx-gma-config_helpers.ads
+++ b/common/hw-gfx-gma-config_helpers.ads
@@ -40,15 +40,15 @@
    use type HW.Pos32;
    pragma Warnings (GNAT, On, """Integer_32"" is already use-visible *");
    function Validate_Config
-     (FB       : Framebuffer_Type;
-      Port_Cfg : Port_Config;
-      Pipe     : Pipe_Index)
+     (FB    : Framebuffer_Type;
+      Mode  : Mode_Type;
+      Pipe  : Pipe_Index)
       return Boolean
    with
       Post =>
         (if Validate_Config'Result then
-            Rotated_Width (FB) <= Port_Cfg.Mode.H_Visible and
-            Rotated_Height (FB) <= Port_Cfg.Mode.V_Visible and
+            Rotated_Width (FB) <= Mode.H_Visible and
+            Rotated_Height (FB) <= Mode.V_Visible and
             (FB.Offset = VGA_PLANE_FRAMEBUFFER_OFFSET or
              FB.Height + FB.Start_Y <= FB.V_Stride));