Document that the new companion-device lookup helper takes a reference
to the companion device which needs to be dropped after use.
Signed-off-by: NJohan Hovold <johan@kernel.org>
Acked-by: NAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>