drm: kirin: Rename ade_plane to kirin_plane

drm: kirin: Rename ade_plane to kirin_plane

As part of refactoring the kirin driver to better support
different hardware revisions, this patch renames the
struct ade_plane to kirin_plane.

The struct kirin_plane will later used by both kirin620 and
future kirin960 driver, and will be moved to a common
kirin_drm_drv.h in a future patch

Cc: Rongrong Zou <zourongrong@gmail.com>
Cc: Xinliang Liu <z.liuxinliang@hisilicon.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: dri-devel <dri-devel@lists.freedesktop.org>
Cc: Sam Ravnborg <sam@ravnborg.org>
Acked-by: Xinliang Liu <z.liuxinliang@hisilicon.com>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Xu YiPing <xuyiping@hisilicon.com>
[jstultz: reworded commit message]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20190820230626.23253-7-john.stultz@linaro.org