drm/vc4: Run DRM default client setup

drm/vc4: Run DRM default client setup

Call drm_client_setup_with_fourcc() to run the kernel's default client
setup for DRM. Set fbdev_probe in struct drm_driver, so that the client
setup can start the common fbdev client.

v5:
- select DRM_CLIENT_SELECTION
v2:
- use drm_client_setup_with_fourcc()

Signed-off-by: Thomas Zimmermann <[email protected]>
Cc: Maxime Ripard <[email protected]>
Cc: Dave Stevenson <[email protected]>
Cc: Raspberry Pi Kernel Maintenance <[email protected]>
Reviewed-by: Dave Stevenson <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]