ARM: dts: msm: Add USB VBUS detect for msm8996 Liquid

On MSM8996 LiQUID the VBUS detection on the primary USB port
is handled by a separate IC which will provide detection status
via GPIO.

Also this circuit will provide 5V VBUS for host mode. The
usb_otg_switch regulator is already defined to control this,
but just needs to be referenced from the USB3 node.

Change-Id: Ifcf07dfd2e825625b5524302d2a6beeaf3a06672
Signed-off-by: Jack Pham <jackp@codeaurora.org>