backend/drm: fix adaptive sync no-op changes

When a compositors submits a wlr_output_state with
WLR_OUTPUT_STATE_ADAPTIVE_SYNC_ENABLED set and
adaptive_sync_enabled = false on an output which doesn't support
adaptive sync, we'd fail the commit. Fix this.

This bug was previously hidden because wlr_output_commit() drops
no-op changes from wlr_output_state.committed.

backend/drm/atomic.c

@@ -276,7 +276,7 @@ bool drm_atomic_connector_prepare(struct wlr_drm_connector_state *state, bool mo
 		output->adaptive_sync_status == WLR_OUTPUT_ADAPTIVE_SYNC_ENABLED;
 	bool vrr_enabled = prev_vrr_enabled;
 	if ((state->base->committed & WLR_OUTPUT_STATE_ADAPTIVE_SYNC_ENABLED)) {
-		if (!drm_connector_supports_vrr(conn)) {
+		if (state->base->adaptive_sync_enabled && !drm_connector_supports_vrr(conn)) {
 			return false;
 		}
 		vrr_enabled = state->base->adaptive_sync_enabled;

backend/drm/legacy.c

@@ -110,10 +110,11 @@ static bool legacy_crtc_commit(const struct wlr_drm_connector_state *state,
 	}
 
 	if (state->base->committed & WLR_OUTPUT_STATE_ADAPTIVE_SYNC_ENABLED) {
-		if (!drm_connector_supports_vrr(conn)) {
+		if (state->base->adaptive_sync_enabled && !drm_connector_supports_vrr(conn)) {
 			return false;
 		}
-		if (drmModeObjectSetProperty(drm->fd, crtc->id, DRM_MODE_OBJECT_CRTC,
+		if (crtc->props.vrr_enabled != 0 &&
+				drmModeObjectSetProperty(drm->fd, crtc->id, DRM_MODE_OBJECT_CRTC,
 				crtc->props.vrr_enabled,
 				state->base->adaptive_sync_enabled) != 0) {
 			wlr_drm_conn_log_errno(conn, WLR_ERROR,