We'll need in some tests to control when the device needs to be added
and removed, so let's split the device creation from the DRM device
creation function.
Reviewed-by: NMaíra Canal <mcanal@igalia.com>
Link: https://lore.kernel.org/r/20221123-rpi-kunit-tests-v3-7-4615a663a84a@cerno.techSigned-off-by: NMaxime Ripard <maxime@cerno.tech>