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/k2e_hs_evm_defconfig b/configs/k2e_hs_evm_defconfig
index ef6abc8..a86eeb8 100644
--- a/configs/k2e_hs_evm_defconfig
+++ b/configs/k2e_hs_evm_defconfig
@@ -29,6 +29,8 @@
 CONFIG_DM=y
 CONFIG_TI_AEMIF=y
 # CONFIG_MMC is not set
+CONFIG_NAND=y
+CONFIG_NAND_DAVINCI=y
 CONFIG_DM_SPI_FLASH=y
 CONFIG_SPI_FLASH=y
 CONFIG_SPI_FLASH_STMICRO=y