Convert CONFIG_OMAP3_SPI to Kconfig

This converts the following to Kconfig:
   CONFIG_OMAP3_SPI

Signed-off-by: Adam Ford <aford173@gmail.com>
[trini: Minor comment tweaks]
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/omap5_uevm_defconfig b/configs/omap5_uevm_defconfig
index 273be58..90dd62a 100644
--- a/configs/omap5_uevm_defconfig
+++ b/configs/omap5_uevm_defconfig
@@ -40,6 +40,7 @@
 CONFIG_MMC_OMAP_HS=y
 CONFIG_SCSI=y
 CONFIG_SYS_NS16550=y
+CONFIG_OMAP3_SPI=y
 CONFIG_USB=y
 CONFIG_USB_EHCI_HCD=y
 CONFIG_USB_DWC3=y