ARM: dts: hummingboard/cubox-i: move usb otg configuration to platform level

The configuration of the USB OTG is a platform configuration decision,
not a microsom decision.  Move this configuration out to the platform
level files.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Shawn Guo <shawn.guo@freescale.com>