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/imx6ul_geam_nand_defconfig b/configs/imx6ul_geam_nand_defconfig
index fcfdb21..9012177 100644
--- a/configs/imx6ul_geam_nand_defconfig
+++ b/configs/imx6ul_geam_nand_defconfig
@@ -52,6 +52,7 @@
 CONFIG_MTD=y
 CONFIG_MTD_RAW_NAND=y
 CONFIG_NAND_MXS=y
+CONFIG_SYS_NAND_ONFI_DETECTION=y
 CONFIG_PHYLIB=y
 CONFIG_PHY_SMSC=y
 CONFIG_FEC_MXC=y