config/output: Skip search if config has a mode

When doing an output configuration search, the intent is to only look
for modes if the output's configuration does not contain a specific
mode. This was done by testing if config_has_auto_mode returned false.

config_has_auto_mode had its return values backwards, leading to other
modes being tested if the output configuration had specified modes or
modelines, leading to unwanted modes being selected.

Invert the function to config_has_manual_mode to give it a clearer name,
and fix the return values in the process.

sway/config/output.c

@@ -651,9 +651,9 @@ struct output_config *find_output_config(struct sway_output *sway_output) {
 	return result;
 }
 
-static bool config_has_auto_mode(struct output_config *oc) {
+static bool config_has_manual_mode(struct output_config *oc) {
 	if (!oc) {
-		return true;
+		return false;
 	}
 	if (oc->drm_mode.type != 0 && oc->drm_mode.type != (uint32_t)-1) {
 		return true;
@@ -754,7 +754,8 @@ static bool search_mode(struct search_context *ctx, size_t output_idx) {
 	struct wlr_output_state *state = &backend_state->base;
 	struct wlr_output *wlr_output = backend_state->output;
 
-	if (!config_has_auto_mode(cfg->config)) {
+	// We only search for mode if one is not explicitly specified in the config
+	if (config_has_manual_mode(cfg->config)) {
 		return search_adaptive_sync(ctx, output_idx);
 	}