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/dra7xx_evm_defconfig b/configs/dra7xx_evm_defconfig
index c7e5bea..424eae2 100644
--- a/configs/dra7xx_evm_defconfig
+++ b/configs/dra7xx_evm_defconfig
@@ -93,6 +93,7 @@
 CONFIG_MTD=y
 CONFIG_MTD_RAW_NAND=y
 CONFIG_SYS_NAND_BLOCK_SIZE=0x20000
+CONFIG_SYS_NAND_ONFI_DETECTION=y
 CONFIG_SYS_NAND_PAGE_COUNT=0x40
 CONFIG_SYS_NAND_PAGE_SIZE=0x800
 CONFIG_SYS_NAND_OOBSIZE=0x40