gma: Introduce Generation type

It's the subset of `CPU_Type` that we have different compilation units
for. Also use it in the `Config` wherever we can decide something purely
on the `Generation` (i.e. don't mix `Gen` and `CPU` in expressions).

Change-Id: I5061021a80cd75ee3d7996ca343e6388b22bf341
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/c/libgfxinit/+/27059
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
diff --git a/common/Makefile.inc b/common/Makefile.inc
index 8d6634e..410eeba 100644
--- a/common/Makefile.inc
+++ b/common/Makefile.inc
@@ -45,6 +45,7 @@
 gfxinit-y += hw-gfx-framebuffer_filler.adb
 gfxinit-y += hw-gfx-framebuffer_filler.ads
 
+CONFIG_GFX_GMA_GENERATION	:= $(call strip_quotes,$(CONFIG_GFX_GMA_GENERATION))
 CONFIG_GFX_GMA_CPU		:= $(call strip_quotes,$(CONFIG_GFX_GMA_CPU))
 CONFIG_GFX_GMA_CPU_VARIANT	:= $(call strip_quotes,$(CONFIG_GFX_GMA_CPU_VARIANT))
 CONFIG_GFX_GMA_INTERNAL_PORT	:= $(call strip_quotes,$(CONFIG_GFX_GMA_INTERNAL_PORT))
@@ -54,7 +55,8 @@
 
 $(hw-gfx-gma-config-ads): $(dir)/hw-gfx-gma-config.ads.template $(cnf)
 	printf "    GENERATE   $(patsubst /%,%,$(subst $(obj)/,,$@))\n"
-	sed -e's/<<CPU>>/$(CONFIG_GFX_GMA_CPU)/' \
+	sed -e's/<<GEN>>/$(CONFIG_GFX_GMA_GENERATION)/' \
+	    -e's/<<CPU>>/$(CONFIG_GFX_GMA_CPU)/' \
 	    -e's/<<CPU_VARIANT>>/$(CONFIG_GFX_GMA_CPU_VARIANT)/' \
 	    -e's/<<INTERNAL_PORT>>/$(CONFIG_GFX_GMA_INTERNAL_PORT)/' \
 	    -e's/<<ANALOG_I2C_PORT>>/$(CONFIG_GFX_GMA_ANALOG_I2C_PORT)/' \