usb: chipidea: add vbus interrupt handler

We add vbus interrupt handler at ci_otg_work, it uses OTGSC_BSV(at otgsc)
to know it is connect or disconnet event.
Meanwhile, we introduce two flags id_event and b_sess_valid_event to
indicate it is an id interrupt or a vbus interrupt.

Tested-by: Marek Vasut <marex@denx.de>
Signed-off-by: Peter Chen <peter.chen@freescale.com>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>