There is a lot of potential to completely get rid of Makefile
and keep everything in Makefile.inc, but for now this declutters
the main Makefile.inc.
Change-Id: I653313c74207f955514c036c81efcbfd988827c9
Signed-off-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Reviewed-on: https://review.coreboot.org/13518
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <martinroth@google.com>