top/Makefile.inc: Define regions-for-file with a flexibility

If we need to put a CBFS chunk into a specific region, add a line in
any Makefile.inc

regions-for-file-xxx=region_name

TODO:Do a complete binary identical test for all the mainboards.

Change-Id: Ie37a8a9230dc8b8e5664be8806f047afb94fba69
Signed-off-by: Zheng Bao <fishbaozi@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/70313
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Martin Roth <martin.roth@amd.corp-partner.google.com>
diff --git a/Makefile.inc b/Makefile.inc
index 7258043..9365a4a 100644
--- a/Makefile.inc
+++ b/Makefile.inc
@@ -823,7 +823,7 @@
 #
 # This is the default implementation. When using a boot strategy employing
 # multiple CBFSes in fmap regions, override it.
-regions-for-file ?= COREBOOT
+regions-for-file ?= $(if $(value regions-for-file-$(1)), $(regions-for-file-$(1)), COREBOOT)
 
 ifeq ($(CONFIG_CBFS_AUTOGEN_ATTRIBUTES),y)
 	cbfs-autogen-attributes=-g