NV12 framebuffers produced by the VPU shows distorted on RK3288
after win has been disabled when scaling is active.

This issue can be reproduced using a 1080p modeset by:
- Scale a 1280x720 NV12 framebuffer to 1920x1080 on win0
- Disable win0
- Display a 1920x1080 NV12 framebuffer without scaling on win0
- Output will now show the framebuffer distorted

And by:
- Scale a 1280x720 NV12 framebuffer to 1920x1080
- Change to a 720p modeset (win gets disabled and scaling reset to none)
- Output will now show the framebuffer distorted

Fix this by setting scale mode to none when win is disabled.

Fixes: 4c156c21 ("drm/rockchip: vop: support plane scale")
Cc: stable@vger.kernel.org
Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Link: https://patchwork.freedesktop.org/patch/msgid/AM3PR03MB0966DE3E19BACE07328CD637AC7D0@AM3PR03MB0966.eurprd03.prod.outlook.com