staging: vc04_services: vchiq_arm: Add new bus type and device type

staging: vc04_services: vchiq_arm: Add new bus type and device type

The devices that the vchiq interface registers (bcm2835-audio,
bcm2835-camera) are implemented and exposed by the VC04 firmware.
The device tree describes the VC04 itself with the resources required
to communicate with it through a mailbox interface. However, the
vchiq interface registers these devices as platform devices. This
also means the specific drivers for these devices are getting
registered as platform drivers. This is not correct and a blatant
abuse of platform device/driver.

Add a new bus type, vchiq_bus_type and device type (struct vchiq_device)
which will be used to migrate child devices that the vchiq interfaces
creates/registers from the platform device/driver.

Signed-off-by: Umang Jain <umang.jain@ideasonboard.com>
Link: https://lore.kernel.org/r/20230923143200.268063-4-umang.jain@ideasonboard.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>