MLK-10101-4 usb: add otg_fsm pointer in usb_bus

MLK-10101-4 usb: add otg_fsm pointer in usb_bus

Add otg_fsm pointer in struct of usb_bus for access otg_fsm via bus.
Original way was to put it in usb_otg, then usb host can access otg_fsm via
hcd->usb_phy->otg->fsm, since usb_phy will not be the future direction, instead
phy is prefered, so this way may not work. It's more direct and simple to put
it in usb_bus.

Signed-off-by: Li Jun <jun.li@freescale.com>