usb: android: Add support for voting against APPS idle standalone PC

Allowing idle standalone PC when USB cable is connected will degrade
mass storage performance numbers. Add support for reading swfi latency
to vote for DMA latency when USB cable is connected.

Change-Id: Id60cc9ef516944c8338c02e450ba849d42465ab1
Signed-off-by: Vijayavardhan Vennapusa <vvreddy@codeaurora.org>