build system: add dependencies for GRUB2 and FILO

Make sure the build system knows how to start building the various
integrated payloads we support.

Change-Id: I2128d09c78795e0a41b055975e9f7052e3d951ee
Signed-off-by: Patrick Georgi <patrick@georgi-clan.de>
Reviewed-on: https://review.coreboot.org/12641
Reviewed-by: Alexander Couzens <lynxis@fe80.eu>
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <martinroth@google.com>
1 file changed