USB: gpio_vbus: wakeup support on GPIO VBUS interrupts

We'd like to see the system waking up from the system-wide suspend
when it gets plugged-in, or the USB cable is pulled out.

Also makes it configurable via platform data 'wakeup'.

Signed-off-by: Shinya Kuribayashi <shinya.kuribayashi.px@renesas.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>