make sure toplevel $(SUBDIRS) is always declared

The $(SUBDIRS) variable is only declared when U-Boot has been configured,
but it gets used all the time.  In the non-configured case, it is used to
generate a helpful error message, but it needs to be set properly for that
to occur.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
1 file changed