Convert CONFIG_SYS_I2C_DAVINCI to Kconfig

This converts the following to Kconfig:
   CONFIG_SYS_I2C_DAVINCI

Signed-off-by: Adam Ford <aford173@gmail.com>
diff --git a/configs/k2l_evm_defconfig b/configs/k2l_evm_defconfig
index 69547c4..8ec43e6 100644
--- a/configs/k2l_evm_defconfig
+++ b/configs/k2l_evm_defconfig
@@ -35,6 +35,7 @@
 CONFIG_ENV_IS_IN_NAND=y
 CONFIG_NET_RANDOM_ETHADDR=y
 CONFIG_DM=y
+CONFIG_SYS_I2C_DAVINCI=y
 CONFIG_TI_AEMIF=y
 # CONFIG_MMC is not set
 CONFIG_NAND=y