Enable usage of KMS modifier

Currently KMS modifiers are disabled due to enabling them causes bandwidth issues when multiple monitors are enabled.

The currently only possible way to avoid this issue is to use the TEST_ONLY atomic mode setting flag to first try out if a multi monitor configuration is possible by constructing a full mode set with all the intended framebuffers.

If it would fail, try with changing the modifiers of the framebuffers allocated and retry, until it no longer fails.