drm/hisilicon: Add plane driver for ADE

Add plane funcs and helper funcs for ADE.

v8: None.
v7: None.
v6: None.
v5: None.
v4: None.
v3:
- A few cleanup.
v2:
- Remove abtraction layer.
Signed-off-by: Xinliang Liu <xinliang.liu@linaro.org>
Signed-off-by: Xinwei Kong <kong.kongxinwei@hisilicon.com>