dwc3-msm: Introduce sysfs param to indicate usb compliance mode

Currently usb stack is teared down if no activity is detected for
10 seconds when floating charger is connected. USB 3.1 compliance
equipment usually reported as floating charger. Introduce sysfs
parameter to indicate if usb compliance in progress and do not
tear down the stack based on this parameter.

Change-Id: I26013c281827f35eac7f21ed68b3880e541d82b9
Signed-off-by: Vamsi Krishna Samavedam <vskrishn@codeaurora.org>