ASoC: rt5668: remove useless assignments

cppcheck warnings:

sound/soc/codecs/rt5668.c:1177:6: style: Redundant initialization for
'idx'. The initialized value is overwritten before it is
read. [redundantInitialization]
 idx = rt5668_div_sel(rt5668, 1500000, div, ARRAY_SIZE(div));
     ^
sound/soc/codecs/rt5668.c:1174:10: note: idx is initialized
 int idx = -EINVAL;
         ^
sound/soc/codecs/rt5668.c:1177:6: note: idx is overwritten
 idx = rt5668_div_sel(rt5668, 1500000, div, ARRAY_SIZE(div));
     ^

sound/soc/codecs/rt5668.c:1202:6: style: Redundant initialization for
'idx'. The initialized value is overwritten before it is
read. [redundantInitialization]
 idx = rt5668_div_sel(rt5668, ref, div, ARRAY_SIZE(div));
     ^
sound/soc/codecs/rt5668.c:1191:25: note: idx is initialized
 int ref, val, reg, idx = -EINVAL;
                        ^
sound/soc/codecs/rt5668.c:1202:6: note: idx is overwritten
 idx = rt5668_div_sel(rt5668, ref, div, ARRAY_SIZE(div));
     ^
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20210302212527.55158-19-pierre-louis.bossart@linux.intel.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/rt5668.c

@@ -1171,7 +1171,7 @@ static int set_dmic_clk(struct snd_soc_dapm_widget *w,
 	struct snd_soc_component *component =
 		snd_soc_dapm_to_component(w->dapm);
 	struct rt5668_priv *rt5668 = snd_soc_component_get_drvdata(component);
-	int idx = -EINVAL;
+	int idx;
 	static const int div[] = {2, 4, 6, 8, 12, 16, 24, 32, 48, 64, 96, 128};
 
 	idx = rt5668_div_sel(rt5668, 1500000, div, ARRAY_SIZE(div));
@@ -1188,7 +1188,7 @@ static int set_filter_clk(struct snd_soc_dapm_widget *w,
 	struct snd_soc_component *component =
 		snd_soc_dapm_to_component(w->dapm);
 	struct rt5668_priv *rt5668 = snd_soc_component_get_drvdata(component);
-	int ref, val, reg, idx = -EINVAL;
+	int ref, val, reg, idx;
 	static const int div[] = {1, 2, 3, 4, 6, 8, 12, 16, 24, 32, 48};
 
 	val = snd_soc_component_read(component, RT5668_GPIO_CTRL_1) &