usb: dwc3:Handle race between composition switch and cable disconnect

The current implementation of handling run/~stop of DCTL based
on state of VBUS or the pullup call from the udc core can
result in a below race condition where the run/~stop is cleared
twice leading to an invalid state of controller.

	Thread -1			Thread-2
	vbus_session (1)

	   spin_lock
	   no run_stop(1) call		pullup(1)
	   spin_unlock			  softconnect = 1
					  vbus_active checked

	vbus_session (0)
	   spin_lock
	   run_stop(0) called
	   spin_unlock

Prevent this by ensuring a proper state transitions and clear
run/~stop only when when there is a transition from ACTIVE
and there is an pullup(0) event or vbus_session(0) call.

Change-Id: I03c4acfc2c6697e02c510d079c7d48d9a82bb322
Signed-off-by: Sriharsha Allenki <sallenki@codeaurora.org>