usb: ohci-sa1111: convert shutdown method to native device_driver

Convert the shutdown method to use the device_driver shutdown function
pointer rather than a private bus-type shutdown.  This is the only user
for SA1111 bus types, so having the support code in the bus doesn't
make any sense.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>