Convert CONFIG_SYS_NAND_ONFI_DETECTION to Kconfig

This converts the following to Kconfig:
   CONFIG_SYS_NAND_ONFI_DETECTION

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/colibri-imx6ull_defconfig b/configs/colibri-imx6ull_defconfig
index f5fd481..0af56f4 100644
--- a/configs/colibri-imx6ull_defconfig
+++ b/configs/colibri-imx6ull_defconfig
@@ -73,6 +73,7 @@
 CONFIG_SYS_NAND_USE_FLASH_BBT=y
 CONFIG_NAND_MXS=y
 CONFIG_NAND_MXS_DT=y
+CONFIG_SYS_NAND_ONFI_DETECTION=y
 CONFIG_MTD_UBI_FASTMAP=y
 CONFIG_PHYLIB=y
 CONFIG_PHY_MICREL=y