Fix building with GCC 4.9

It doesn't like empty initializers.

Change-Id: If2988e60401155f87ee3369c77f00ccf9332012c
Signed-off-by: Evgeny Zinoviev <me@ch1p.io>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/36629


Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>