ASoC: simple-card-utils: remove both playback/capture_only check

soc-pcm.c :: soc_get_playback_capture() will indicate error
if both playback_only / capture_only were true.

Thus, graph_util_parse_link_direction() which setup playback_only /
capture_only don't need to check it.
And, its return value is not used on existing driver. Let's remove it.
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Link: https://msgid.link/r/87a5kah6gm.wl-kuninori.morimoto.gx@renesas.comSigned-off-by: Mark Brown <broonie@kernel.org>

include/sound/simple_card_utils.h

@@ -197,7 +197,7 @@ int graph_util_is_ports0(struct device_node *port);
 int graph_util_parse_dai(struct device *dev, struct device_node *ep,
 			 struct snd_soc_dai_link_component *dlc, int *is_single_link);
 
-int graph_util_parse_link_direction(struct device_node *np,
+void graph_util_parse_link_direction(struct device_node *np,
 				    bool *is_playback_only, bool *is_capture_only);
 
 #ifdef DEBUG

sound/soc/generic/simple-card-utils.c

@@ -1140,7 +1140,7 @@ int graph_util_parse_dai(struct device *dev, struct device_node *ep,
 }
 EXPORT_SYMBOL_GPL(graph_util_parse_dai);
 
-int graph_util_parse_link_direction(struct device_node *np,
+void graph_util_parse_link_direction(struct device_node *np,
 				    bool *playback_only, bool *capture_only)
 {
 	bool is_playback_only = false;
@@ -1149,13 +1149,8 @@ int graph_util_parse_link_direction(struct device_node *np,
 	is_playback_only = of_property_read_bool(np, "playback-only");
 	is_capture_only = of_property_read_bool(np, "capture-only");
 
-	if (is_playback_only && is_capture_only)
-		return -EINVAL;
-
 	*playback_only = is_playback_only;
 	*capture_only = is_capture_only;
-
-	return 0;
 }
 EXPORT_SYMBOL_GPL(graph_util_parse_link_direction);