gma: Give GM45 its own designation (separate from G45)

While G45 and GM45 have mostly the same display engine (seem to
only differ in the available outputs), they are driven by very
different clock sources. To derive the corret CDClk in a later
commit, we'll have to distinguish between the two.

Change-Id: I99bbd0582a03a9e2806ef2ebf63e466ec40133b3
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/c/libgfxinit/+/35711
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
diff --git a/common/hw-gfx-gma.ads b/common/hw-gfx-gma.ads
index f9444e8..353ec4b 100644
--- a/common/hw-gfx-gma.ads
+++ b/common/hw-gfx-gma.ads
@@ -37,6 +37,7 @@
 
    type CPU_Type is
      (G45,
+      GM45,
       Ironlake,
       Sandybridge,
       Ivybridge,