gma panel: Introduce `Panel_Control` type

For now, `Panel_Control` only distinguishes `Panel_1` from `No_Panel`,
i.e. if a port has a panel attached or not. To ease future addition of
support for more than one panel, we already add loops and arrays around
it, though.

With the information, if a port has a panel attached, in `Port_Config`,
we can pass that on into Panel.* procedures and let those decide what
to do (e.g. do nothing if no panel is attached).

Change-Id: I83864bc86b48f65d9ba43e083b805ca09497cbb0
Signed-off-by: Nico Huber <nico.huber@secunet.com>
Reviewed-on: https://review.coreboot.org/c/libgfxinit/+/38243
Tested-by: Nico Huber <nico.h@gmx.de>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
diff --git a/common/hw-gfx-gma.ads b/common/hw-gfx-gma.ads
index fcd8804..0c44434 100644
--- a/common/hw-gfx-gma.ads
+++ b/common/hw-gfx-gma.ads
@@ -253,11 +253,15 @@
    subtype PCH_HDMI_Port is PCH_Port range PCH_HDMI_B .. PCH_HDMI_D;
    subtype PCH_DP_Port is PCH_Port range PCH_DP_B .. PCH_DP_D;
 
+   type Panel_Control is (No_Panel, Panel_1);
+   subtype Valid_Panels is Panel_Control range Panel_1 .. Panel_1;
+
    type Port_Config is
       record
          Port     : GPU_Port;
          PCH_Port : GMA.PCH_Port;
          Display  : Display_Type;
+         Panel    : Panel_Control;
          Mode     : Mode_Type;
          Is_FDI   : Boolean;
          FDI      : DP_Link;