Convert CONFIG_OMAP_USB_PHY to Kconfig

This converts the following to Kconfig:
   CONFIG_OMAP_USB_PHY

Signed-off-by: Adam Ford <aford173@gmail.com>
diff --git a/drivers/usb/phy/Kconfig b/drivers/usb/phy/Kconfig
index 943a966..a202fd1 100644
--- a/drivers/usb/phy/Kconfig
+++ b/drivers/usb/phy/Kconfig
@@ -10,3 +10,6 @@
 config TWL4030_USB
 	bool "TWL4030 PHY"
 
+config OMAP_USB_PHY
+	bool "OMAP PHY"
+