drm: xlnx: zynqmp: Use drm helpers when calculating buffer sizes

drm: xlnx: zynqmp: Use drm helpers when calculating buffer sizes

Use drm helpers, drm_format_info_plane_width(),
drm_format_info_plane_height() and drm_format_info_min_pitch() to
calculate sizes for the DMA.

This cleans up the code, but also makes it possible to support more
complex formats (like P030, P230).

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Link: https://patch.msgid.link/20260423-xilinx-formats-v10-7-c690c2b8ea89@ideasonboard.com
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>