mei: bus: change remove callback to return void

mei: bus: change remove callback to return void

The driver core ignores the return value of mei_cl_device_remove() so
passing an error value doesn't solve any problem. As most mei drivers'
remove callbacks return 0 unconditionally and returning a different value
doesn't have any effect, change this prototype to return void and return 0
unconditionally in mei_cl_device_remove(). The only driver that could
return an error value is modified to emit an explicit warning in the error
case.

Acked-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Uwe Kleine-König <uwe@kleine-koenig.org>
Link: https://lore.kernel.org/r/20210208073705.428185-3-uwe@kleine-koenig.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>