dt-bindings: usb: Add binding for the TI wrapper for Cadence USB3 controller

TI platforms have a wrapper module around the Cadence USB3
controller. Add binding information for that.

Signed-off-by: Roger Quadros <rogerq@ti.com>
Cc: Rob Herring <robh@kernel.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>