If onboard_hub_power_off() called by onboard_hub_remove() fails it emits
an error message. Forwarding the returned error value to the driver core
results in another error message. As the return value is otherwise
ignored, just drop the return value. There is no side effect apart from
suppressing the core's warning.

Instead of returning zero unconditionally, convert to .remove_new()
which has the same semantics as .remove() that unconditionally returns
zero.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20230530073633.2193618-1-u.kleine-koenig@pengutronix.deSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>