Convert CONFIG_DAVINCI_SPI to Kconfig

This converts the following to Kconfig:
   CONFIG_DAVINCI_SPI

Signed-off-by: Adam Ford <aford173@gmail.com>
diff --git a/configs/k2hk_evm_defconfig b/configs/k2hk_evm_defconfig
index 7115443..1e3905f 100644
--- a/configs/k2hk_evm_defconfig
+++ b/configs/k2hk_evm_defconfig
@@ -44,6 +44,7 @@
 CONFIG_DM_SERIAL=y
 CONFIG_SYS_NS16550=y
 CONFIG_DM_SPI=y
+CONFIG_DAVINCI_SPI=y
 CONFIG_USB=y
 CONFIG_USB_XHCI_HCD=y
 CONFIG_USB_XHCI_DWC3=y