USB: autosuspend for usblcd

this patch implements autosuspend for the usblcd driver. It uses
the new usb_anchor infrastructure. Many thanks to Georges for testing.

Signed-off-by: Oliver Neukum <oneukum@suse.de>
Cc: Georges Toth <g.toth@e-biz.lu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>