Since support for Openblocks A6 was introduced in 2014 and commit
906afb533186 ("ARM: mvebu: Add Plat'home's Kirkwood Openblocks A6 board
support") there is no kwbimage config. This patch guesses such a file
that at least makes barebox compile again with
CONFIG_MACH_PLATHOME_OPENBLOCKS_A6=y.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>