Convert CONFIG_USB_EHCI_MX5 to Kconfig

This converts the following to Kconfig:
   CONFIG_USB_EHCI_MX5

Signed-off-by: Lukasz Majewski <lukma@denx.de>
diff --git a/drivers/usb/host/Kconfig b/drivers/usb/host/Kconfig
index 0fbc115..1c2212f 100644
--- a/drivers/usb/host/Kconfig
+++ b/drivers/usb/host/Kconfig
@@ -132,6 +132,13 @@
 	---help---
 	  Enables support for the on-chip EHCI controller on MVEBU SoCs.
 
+config USB_EHCI_MX5
+	bool "Support for i.MX5 on-chip EHCI USB controller"
+	depends on ARCH_MX5
+	default n
+	help
+	  Enables support for the on-chip EHCI controller on i.MX5 SoCs.
+
 config USB_EHCI_MX6
 	bool "Support for i.MX6 on-chip EHCI USB controller"
 	depends on ARCH_MX6