Neatly reduce displayid boilerplate in code. No functional changes.
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/e50f876cecbfee369da887ad19350eee0d89b87f.1617024940.git.jani.nikula@intel.com