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>
diff --git a/include/configs/km/keymile-common.h b/include/configs/km/keymile-common.h
index 851b13e..ad0041d 100644
--- a/include/configs/km/keymile-common.h
+++ b/include/configs/km/keymile-common.h
@@ -32,9 +32,6 @@
  */
 #define CONFIG_BOOTP_BOOTFILESIZE
 
-/* UBI Support for all Keymile boards */
-#define CONFIG_MTD_CONCAT
-
 #ifndef CONFIG_KM_DEF_ENV_BOOTPARAMS
 #define CONFIG_KM_DEF_ENV_BOOTPARAMS \
 	"actual_bank=0\0"