usb: chipidea: support runtime power management for otg fsm mode

This patch adds runtime power management support for otg fsm mode, since
A-device in a_idle state cannot detect data pulse irq after suspended, here
enable wakeup by connection before suspend to make it can be resumed by DP;
and handle wakeup from that state like SRP.

Signed-off-by: Li Jun <jun.li@freescale.com>
Signed-off-by: Peter Chen <peter.chen@freescale.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
