gma: Introduce `PCH_Type`

We got this far without it but now there is a PCH (Cannon Point)
that is not fully compatible to its predecessors but works with
the same CPUs. First, introduce the type and make use of it in a
few cases. In a follow-up, we'll add the new PCH.

Change-Id: I9d4965f110da3613749023143cf75123e63ae76e
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/c/libgfxinit/+/48762
Reviewed-by: Michael Niewöhner <foss@mniewoehner.de>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
diff --git a/common/hw-gfx-gma.ads b/common/hw-gfx-gma.ads
index 1215fc5..b6c491f 100644
--- a/common/hw-gfx-gma.ads
+++ b/common/hw-gfx-gma.ads
@@ -49,6 +49,13 @@
 
    type CPU_Variant is (Normal, ULT, ULX);
 
+   type PCH_Type is
+     (No_PCH,
+      Ibex_Peak,
+      Cougar_Point,     -- Panther Point compatible
+      Lynx_Point,       -- Wildcat Point compatible
+      Sunrise_Point);   -- Union Point compatible
+
    type Port_Type is
      (Disabled,
       LVDS,