OMAP: OHCI: hc_driver's stop method should call ohci_stop

Without this, the ohci-omap driver will not cleanup the debugfs
nodes when the driver is unloaded. So the next insmod will fail,
if CONFIG_DEBUG_FS and CONFIG_USB_DEBUG are both selected.
Reported-by: Nvikram pandita <vikram.pandita@ti.com>
Cc: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: NAnand Gadiyar <gadiyar@ti.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>