km/common: remove CONFIG_MTD_CONCAT

This was used for a board which is not supproted anymore and can
therefore be dropped.

CC: Stefan Roese <sr@denx.de>
Signed-off-by: Holger Brunck <holger.brunck@hitachi-powergrids.com>
Reviewed-by: Stefan Roese <sr@denx.de>
1 file changed