drm/tests: Add tests for drm_connector_dynamic_init()/register()

Add kunit tests for
drm_connector_dynamic_init()/drm_connector_dynamic_register() added in
an earlier commit.

v2: Replace the reference to the patchset with "earlier commit". (Jani)

Suggested-by: Maxime Ripard <[email protected]>
Reviewed-by: Lyude Paul <[email protected]>
Reviewed-by: Jani Nikula <[email protected]>
Acked-by: Alex Deucher <[email protected]>
Reviewed-by: Maxime Ripard <[email protected]>
Signed-off-by: Imre Deak <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]

Author: ideak