drm: zynq_drm: drv: Remove unused fields of format_info

Remove unused fields(bpp, yuv) from struct zynq_drm_format_info.

Signed-off-by: hyun woo kwon <hyunk@xilinx.com>
drm: zynq_drm: Remove empty descriptions

Remove empty descriptions.

Signed-off-by: hyun woo kwon <hyunk@xilinx.com>