backends/drm: use closefb instead of removefb when available
The closefb ioctl removes the userspace reference from the framebuffer but does not try to disable planes and outputs if the buffer is still used. This allows for example for smoother transitions between SDDM and the Plasma session
draft until https://lore.kernel.org/dri-devel/20231016142510.3109-2-contact@emersion.fr/ is merged upstream
Edited by Xaver Hugl