imx-drm: ipuv3-plane: move stride setting out of base setup

Setting the stride can only be done on inactive channels, while
the buffer base address can also be updated for running channels
using the hardware double buffering feature.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>