drm/rockchip: vop: fix crtc size in plane check

If the geometry of a crtc is changing in an atomic update then we must
validate the plane size against the new state of the crtc and not the
current size, otherwise if the crtc size is increasing the plane will be
cropped at the previous size and will not fill the screen.

Signed-off-by: John Keeping <john@metanate.com>