staging: fieldbus: anybus: Make remove callback return void

The driver core ignores the return value of struct bus_type::remove()
because there is only little that can be done. To simplify the quest to
make this function return void, let struct
anybuss_client_driver::remove() return void, too. All users already
unconditionally return 0, this commit makes it obvious that returning an
error code is a bad idea.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20210505202923.198607-1-u.kleine-koenig@pengutronix.de


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>