gma adl: Add missing Alder Lake power & clock bits

Most notable changes are:
* ADL-P has different default CDClk frequency choices.
* There are new divisors for CDClk:
  + 3 (resulting in an odd `/ 1.5` for CDClk x2)
  + and 8.
* There are four DBUF slices now and we need to enable all of
  them (probably related to their position and distance to the
  display pipelines on the MBus).
* Programming of MBus ABOX credits is not needed anymore
  (Has_Mbus_Abox_Credits).
* The MBus configuration allows joining of DBUF slices. We
  enable this for our simple buffer allocation (Has_Mbus_Joining)
  (this could use a deeper investigation if we wanted to conserve
  power).

This is based on work by several authors that was originally
squashed into another commit:
https://review.coreboot.org/c/libgfxinit/+/67801/

Change-Id: I6402b9cdcc3571128d76026aa5c7c1bb48f8df33
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.sourcearcade.org/c/libgfxinit/+/510
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Tested-by: Ada SPARK <gnatbot@sourcearcade.org>
Reviewed-by: Thomas Heijligen <src@posteo.de>
diff --git a/common/hw-gfx-gma-config.ads.template b/common/hw-gfx-gma-config.ads.template
index 43c43d5..47316ec 100644
--- a/common/hw-gfx-gma-config.ads.template
+++ b/common/hw-gfx-gma-config.ads.template
@@ -248,8 +248,10 @@
    Need_Pipe_Arb_Slots           : <genbool> := AlderlakeP_On;
 
    ----------- Planes -----------
+   Has_Mbus_Abox_Credits         : <genbool> := Gen_Tigerlake;
    Has_Mbus_Dbox_Credits         : <genbool> := Tigerlake_On;
    Has_New_Mbus_Dbox_Credits     : <genbool> := AlderlakeP_On;
+   Has_Mbus_Joining              : <genbool> := AlderlakeP_On;
    Has_Wide_Watermarks           : <genbool> := Tigerlake_On;
    Has_Plane_Color_Control       : <genbool> := Tigerlake_On;