kconfig: introduce kconfig for UBI

move the UBI config options into Kconfig.

Signed-off-by: Heiko Schocher <hs@denx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Andrew F. Davis <afd@ti.com>
Reviewed by: Evgeni Dobrev <evgeni at studio-punkt.com>
diff --git a/configs/a4m2k_defconfig b/configs/a4m2k_defconfig
index 3f2a58a..aa09bf5 100644
--- a/configs/a4m2k_defconfig
+++ b/configs/a4m2k_defconfig
@@ -19,5 +19,6 @@
 CONFIG_CMD_PING=y
 CONFIG_CMD_LINK_LOCAL=y
 CONFIG_CMD_CACHE=y
+CONFIG_CMD_UBI=y
 CONFIG_LIB_RAND=y
 CONFIG_OF_LIBFDT=y