ASoC: sti: fix return value check in uni_player_parse_dt_audio_glue()

In case of error, the function syscon_regmap_lookup_by_phandle() returns
ERR_PTR() and never returns NULL. The NULL test in the return value check
should be replaced with IS_ERR().
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/sti/uniperif_player.c

@@ -1029,9 +1029,9 @@ static int uni_player_parse_dt_audio_glue(struct platform_device *pdev,
 
 	regmap = syscon_regmap_lookup_by_phandle(node, "st,syscfg");
 
-	if (!regmap) {
+	if (IS_ERR(regmap)) {
 		dev_err(&pdev->dev, "sti-audio-clk-glue syscf not found\n");
-		return -EINVAL;
+		return PTR_ERR(regmap);
 	}
 
 	player->clk_sel = regmap_field_alloc(regmap, regfield[0]);