siox: Don't pass the reference on a master in siox_master_register()

While it's technically fine to pass the ownership of the reference on
a struct siox_master from the caller of siox_master_register() to the
framework this is hard to use. Instead let the framework take its own
reference (that is freed in siox_master_unregister()) and drop the bus
driver's reference in its remove callback.

Acked-by: Thorsten Scherer <t.scherer@eckelmann.de>
Link: https://lore.kernel.org/r/1e8d09d17848e58e8fc6a46278b5e8fb0cf4618a.1708328466.git.u.kleine-koenig@pengutronix.de


Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>