util/amdfwtool: build amdfwtool only for all tools or AMD CPUs

When we're building non-AMD processors, don't bother building amdfwtool
unless we're specifically building all of the tools like for abuild.

Change-Id: I9021674a06d65a79e24020790d317ab947c505fe
Signed-off-by: Martin Roth <gaumless@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/80714
Reviewed-by: Felix Singer <service+coreboot-gerrit@felixsinger.de>
Reviewed-by: Nico Huber <nico.h@gmx.de>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

Makefile

@@ -141,6 +141,12 @@ NOCOMPILE:=
 endif
 endif
 
+# When building the "tools" target, the BUILD_ALL_TOOLS variable needs
+# to be set before reading the tools' Makefiles
+ifneq ($(filter tools, $(MAKECMDGOALS)), )
+BUILD_ALL_TOOLS:=1
+endif
+
 $(xcompile): util/xcompile/xcompile
 	rm -f $@
 	$< $(XGCCPATH) > $@.tmp