apq8016-sbc board is using Dual SPDT USB Switch (TC7USB40MU),
witch is controlled by GPIO to de/multiplex D+/D- USB lines to
USB2513B Hub and uB connector. Add support for this.

Signed-off-by: Ivan T. Ivanov <ivan.ivanov@linaro.org>
Signed-off-by: Felipe Balbi <balbi@ti.com>