dm: atmel: Add driver model support for the ehci driver

Add driver model support while retaining the existing legacy code.
This allows the driver to support boards that have converted to
driver model as well as those that have not.

Signed-off-by: Wenyou Yang <wenyou.yang@atmel.com>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/usb/host/Kconfig b/drivers/usb/host/Kconfig
index 31eec0a..e0699d4 100644
--- a/drivers/usb/host/Kconfig
+++ b/drivers/usb/host/Kconfig
@@ -57,6 +57,13 @@
 
 if USB_EHCI_HCD
 
+config USB_EHCI_ATMEL
+	bool  "Support for Atmel on-chip EHCI USB controller"
+	depends on ARCH_AT91
+	default y
+	---help---
+	  Enables support for the on-chip EHCI controller on Atmel chips.
+
 config USB_EHCI_MARVELL
 	bool "Support for MVEBU (AXP / A38x) on-chip EHCI USB controller"
 	depends on ARCH_MVEBU