Convert CONFIG_NAND_DAVINCI to Kconfig

This converts the following to Kconfig:
   CONFIG_NAND_DAVINCI

Signed-off-by: Adam Ford <aford173@gmail.com>
diff --git a/configs/k2g_hs_evm_defconfig b/configs/k2g_hs_evm_defconfig
index 04f4b02..174af79 100644
--- a/configs/k2g_hs_evm_defconfig
+++ b/configs/k2g_hs_evm_defconfig
@@ -29,6 +29,8 @@
 # CONFIG_BLK is not set
 CONFIG_DM_MMC=y
 CONFIG_MMC_OMAP_HS=y
+CONFIG_NAND=y
+CONFIG_NAND_DAVINCI=y
 CONFIG_DM_SPI_FLASH=y
 CONFIG_SPI_FLASH=y
 CONFIG_SPI_FLASH_BAR=y