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/kmcent2_defconfig b/configs/kmcent2_defconfig
index dafd5da..703db9f 100644
--- a/configs/kmcent2_defconfig
+++ b/configs/kmcent2_defconfig
@@ -59,6 +59,7 @@
 CONFIG_FLASH_CFI_MTD=y
 CONFIG_SYS_FLASH_CFI=y
 CONFIG_MTD_RAW_NAND=y
+CONFIG_SYS_NAND_ONFI_DETECTION=y
 CONFIG_PHYLIB=y
 CONFIG_PHYLIB_10G=y
 CONFIG_PHY_MARVELL=y