drm/rockchip: Support YUV formats with U/V swapped

The VOP in Rockchip SoCs that support YUV planes also support swapping
of the U and V elements. Supporting the swapped variants, especially
NV21, would be beneficial for multimedia applications, as the hardware
video decoders only output NV21, and supporting this pixel format in
the display pipeline would allow the decoded video frames to be output
directly.

Add support for this to support the various formats that have U/V
swapped.

Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20220114074038.2633848-1-wenst@chromium.org