kbuild: automatically include northbridges

This change switches all northbridge vendors and southbridges
to be autoincluded by Makefile.inc, rather than having to be
mentioned explicitly in northbridge/Makefile.inc or in
northbridge/<vendor>/Makefile.inc.

This means, vendor and northbridge directories are now "drop
in", e.g. be placed in the coreboot directory hierarchy
without having to modify any higher level coreboot files.

The long term plan is to enable out of tree components to be
built with a given coreboot version (given that the API did not
change).

Change-Id: I8468154dbfaaaffcba9fda27ba2d7b9049ad5c19
Signed-off-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Reviewed-on: http://review.coreboot.org/9800
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

Makefile.inc

@@ -54,8 +54,8 @@ PHONY+= clean-abuild coreboot lint lint-stable build-dirs
 # root source directories of coreboot
 subdirs-y := src/lib src/console src/device
 subdirs-y += src/ec/acpi $(wildcard src/ec/*/*) $(wildcard src/southbridge/*/*)
-subdirs-y += $(wildcard src/soc/*/*)
-subdirs-y += src/northbridge src/superio src/drivers src/cpu src/vendorcode
+subdirs-y += $(wildcard src/soc/*/*) $(wildcard src/northbridge/*/*)
+subdirs-y += src/superio src/drivers src/cpu src/vendorcode
 subdirs-y += util/cbfstool util/sconfig util/nvramtool util/broadcom
 subdirs-y += $(wildcard src/arch/*)
 subdirs-y += src/mainboard/$(MAINBOARDDIR)