i3c: master: Enhance i3c_bus_type visibility for device searching & event monitoring

Improve the visibility of i3c_bus_type to facilitate searching for
i3c devices attached to the i3c bus. Enable other drivers to use
bus_register_notifier to monitor i3c bus device events.

Signed-off-by: Bhoomik Gupta <bhoomik.gupta@nxp.com>
Link: https://lore.kernel.org/r/20240708053835.3003986-1-bhoomik.gupta@nxp.com


Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>