ARM: dts: msm: Add android-usb-swfi-latency property to APQ8084

While USB cable is connected, USB driver is waiting for interrupts
for resuming of data/control transfers. LPM levels of apq8084 define
1us as the max required latency for the CPU to wake up from idle
state (WFI) and still be able to handle interrupts correctly. (see
arch/arm/boot/dts/apq8084-pm.dtsi)

Setting this flag allows the Android USB driver to add a vote to the
CPU-idle subsystem to ensure that the CPU will not enter any idle state
with a wakeup penalty greater than 1us when the USB cable is connected.

Change-Id: I4c54d5f3310252adc4fe06ad9b09c2a1442464d7
Signed-off-by: Jack Pham <jackp@codeaurora.org>