drm/imx/dcss: allow using nearest neighbor interpolation scaling

This patch adds support for using NN interpolation scaling by setting the
SCALING_FILTER plane property to 1. Otherwise, the default method is used.

Signed-off-by: Laurentiu Palcu <laurentiu.palcu@oss.nxp.com>
Reviewed-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20201105145018.27255-1-laurentiu.palcu@oss.nxp.com