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/twister_defconfig b/configs/twister_defconfig
index f024659..f419140 100644
--- a/configs/twister_defconfig
+++ b/configs/twister_defconfig
@@ -20,6 +20,7 @@
 CONFIG_CMD_CACHE=y
 CONFIG_CMD_EXT2=y
 CONFIG_CMD_FAT=y
+CONFIG_CMD_UBI=y
 CONFIG_SYS_NS16550=y
 CONFIG_USB=y
 CONFIG_USB_ULPI_VIEWPORT_OMAP=y