backends/drm: fix properties not being applied when a modeset is not needed
When testing whether or not a modeset is needed, all that gets tested is whether or not the kernel would allow the commit to happen without the ALLOW_MODESET flag. If there's properties that are only changed in DrmPipeline::prepareAtomicModeset, we need to apply those in the next commit, regardless of whether or not the ALLOW_MODESET flag is necessary.
I tested this with the overscan setting. On AMD changing it doesn't require a modeset, so without this commit it only gets applied once you do the next change that does require one (like changing the display mode). With this commit, it gets applied immediately, like you'd expect.
Edited by Xaver Hugl