usb: phy: Handle per-PHY event for connnect and disconnect events

When usb is connected and enumerated in device mode or when
usb is disconnected, call usb_phy_set_event() from phy drivers
to handle per-PHY event.

[ toddpoynor@google.com : Original patch in Android ]

Cc: Felipe Balbi <balbi@ti.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-kernel@vger.kernel.org
Cc: linux-usb@vger.kernel.org
Cc: Android Kernel Team <kernel-team@android.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Arve Hjønnevåg <arve@android.com>
Cc: Benoit Goby <benoit@android.com>
Cc: Todd Poynor <toddpoynor@google.com>
Signed-off-by: Kiran Raparthy <kiran.kumar@linaro.org>
Signed-off-by: Felipe Balbi <balbi@ti.com>