power: supply: mt6370: Fix missing error code in mt6370_chg_toggle_cfo()

When mt6370_chg_field_get() suceeds, ret is set to zero and returning
zero when flash led is still in strobe mode looks incorrect.

Fixes: 233cb8a4 ("power: supply: mt6370: Add MediaTek MT6370 charger driver")
Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: ChiaEn Wu <chiaen_wu@richtek.com>
Link: https://lore.kernel.org/r/20230906084815.2827930-1-harshit.m.mogalapalli@oracle.comSigned-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

drivers/power/supply/mt6370-charger.c

@@ -324,7 +324,7 @@ static int mt6370_chg_toggle_cfo(struct mt6370_priv *priv)
 
 	if (fl_strobe) {
 		dev_err(priv->dev, "Flash led is still in strobe mode\n");
-		return ret;
+		return -EINVAL;
 	}
 
 	/* cfo off */