usb: phy: qmp: Call chain notifier for cable connect/disconnect

USB PHY base already has an atomic notifier chain that clients can
register for using usb_register_notifier(). Use the call chain to
indicate cable connect and disconnect status for interested clients.

Change-Id: I73f7df8fbd14cb2ee99739d6f7b6cc946fb1783c
Signed-off-by: Jack Pham <jackp@codeaurora.org>