arm: mx6: cm-fx6: force host mode on usb controller

On some CM-FX6 modules U-Boot attempts to configure the usb0 controller in
device mode, which renders it unavailable:
	USB0:   Port not available.
and also causes usb stop to report an error
	EHCI failed to shut down host controller.

This happens mostly on MX6 Dual based modules, and is caused by the USBPHY_CTRL
register reporting USBPHY_CTRL_OTG_ID to be 1, even when it is pulled down.
Since we do not support device mode in cm-fx6 u-boot, force all controllers to
be configured as hosts.

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>