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/db-88f6820-amc_defconfig b/configs/db-88f6820-amc_defconfig
index af8c372..0bb0d59 100644
--- a/configs/db-88f6820-amc_defconfig
+++ b/configs/db-88f6820-amc_defconfig
@@ -59,6 +59,7 @@
 CONFIG_MTD_RAW_NAND=y
 CONFIG_SYS_NAND_USE_FLASH_BBT=y
 CONFIG_NAND_PXA3XX=y
+CONFIG_SYS_NAND_ONFI_DETECTION=y
 CONFIG_SF_DEFAULT_BUS=1
 CONFIG_SPI_FLASH_BAR=y
 CONFIG_SPI_FLASH_MACRONIX=y