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/da850evm_direct_nor_defconfig b/configs/da850evm_direct_nor_defconfig
index b00eea7..0d8a14e 100644
--- a/configs/da850evm_direct_nor_defconfig
+++ b/configs/da850evm_direct_nor_defconfig
@@ -43,3 +43,4 @@
 CONFIG_SPI_FLASH_WINBOND=y
 CONFIG_SYS_NS16550=y
 CONFIG_DM_SPI=y
+CONFIG_DAVINCI_SPI=y