drm/imx: ipuv3 plane: Replace dev_info with dev_dbg if a plane's CRTC changes

This patch changes the dev_info() call to dev_dbg() in ipu_plane_update()
to print out the information that a plane's CRTC is changed, because this
kind of information is only useful for debugging.

Signed-off-by: Liu Ying <Ying.Liu@freescale.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>