arm: mx6: usb: kconfig: add USB_EHCI_MX6 kconfig option

Add USB_EHCI_MX6 option to menuconfig and use it when migrating cm-fx6 usb
config to defconfig.

Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Marek Vasut <marex@denx.de>
Cc: Stefano Babic <sbabic@denx.de>
Cc: Igor Grinberg <grinberg@compulab.co.il>
Signed-off-by: Nikita Kiryanov <nikita@compulab.co.il>
Acked-by: Igor Grinberg <grinberg@compulab.co.il>
diff --git a/drivers/usb/host/Kconfig b/drivers/usb/host/Kconfig
index 8705c7c..b30b43d 100644
--- a/drivers/usb/host/Kconfig
+++ b/drivers/usb/host/Kconfig
@@ -52,6 +52,13 @@
 
 if USB_EHCI_HCD
 
+config USB_EHCI_MX6
+	bool "Support for i.MX6 on-chip EHCI USB controller"
+	depends on ARCH_MX6
+	default y
+	---help---
+	  Enables support for the on-chip EHCI controller on i.MX6 SoCs.
+
 config USB_EHCI_UNIPHIER
 	bool "Support for UniPhier on-chip EHCI USB controller"
 	depends on ARCH_UNIPHIER && OF_CONTROL