ARM: dts: msm: Enable USB3 power collapse on MSM8994

Add property flags to the USB3 device which allow power
collapsing the USB3 controller. This is needed for
increased power savings when the cable is disconnected.

Change-Id: Ic31bc8478de2c449692545936b0b82dab5c05c4c
Signed-off-by: Jack Pham <jackp@codeaurora.org>