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-config.ads.template b/common/hw-gfx-gma-config.ads.template
index 8711e54..1f6fea6 100644
--- a/common/hw-gfx-gma-config.ads.template
+++ b/common/hw-gfx-gma-config.ads.template
@@ -27,7 +27,7 @@
          when Skylake   => Skylake);
    CPU_Last : constant CPU_Type :=
      (case Gen is
-         when G45       => G45,
+         when G45       => GM45,
          when Ironlake  => Ivybridge,
          when Haswell   => Broadwell,
          when Broxton   => Broxton,
@@ -407,8 +407,8 @@
    function Is_GPU (Device_Id : Word16; CPU : CPU_Type; CPU_Var : CPU_Variant)
       return Boolean is
      (case CPU is
-         when G45          => (Device_Id and 16#ff02#) = 16#2e02# or
-                              (Device_Id and 16#fffe#) = 16#2a42#,
+         when G45          => (Device_Id and 16#ff02#) = 16#2e02#,
+         when GM45         => (Device_Id and 16#fffe#) = 16#2a42#,
          when Ironlake     => (Device_Id and 16#fff3#) = 16#0042#,
          when Sandybridge  => (Device_Id and 16#ffc2#) = 16#0102#,
          when Ivybridge    => (Device_Id and 16#ffc3#) = 16#0142#,