drm: bridge: analogix: Destroy connector & encoder when unbinding

Normally we do this in drm_mode_config_cleanup. But:
1/ analogix dp's connector is allocated in bind, and freed after unbind.
So we need to destroy it in unbind to avoid further access.
2/ the drm bridge is attached in bind, and detached in encoder cleanup.
So we need to destroy encoder in unbind.

Signed-off-by: Jeffy Chen <jeffy.chen@rock-chips.com>
Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: http://patchwork.freedesktop.org/patch/msgid/1491481885-13775-5-git-send-email-jeffy.chen@rock-chips.com