USB: EHCI: suppress unwanted error messages

This patch (as1096) fixes an annoying problem: When a full-speed or
low-speed device is plugged into an EHCI controller, it fails to
enumerate at high speed and then is handed over to the companion
controller.  But usbcore logs a misleading and unwanted error message
when the high-speed enumeration fails.

The patch adds a new HCD method, port_handed_over, which asks whether
a port has been handed over to a companion controller.  If it has, the
error message is suppressed.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
CC: David Brownell <david-b@pacbell.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>