ASoC: tlv320aic32x4: Remove set but not used variable 'mclk_rate'

Fixes gcc '-Wunused-but-set-variable' warning:

sound/soc/codecs/tlv320aic32x4.c: In function 'aic32x4_setup_clocks':
sound/soc/codecs/tlv320aic32x4.c:669:16: warning: variable 'mclk_rate' set but not used [-Wunused-but-set-variable]

It is not used since introduction in
commit 96c3bb00 ("ASoC: tlv320aic32x4: Dynamically Determine Clocking")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/tlv320aic32x4.c

@@ -684,9 +684,8 @@ static int aic32x4_setup_clocks(struct snd_soc_component *component,
 	u8 madc, nadc, mdac, ndac, max_nadc, min_mdac, max_ndac;
 	u8 dosr_increment;
 	u16 max_dosr, min_dosr;
-	unsigned long mclk_rate, adc_clock_rate, dac_clock_rate;
+	unsigned long adc_clock_rate, dac_clock_rate;
 	int ret;
-	struct clk *mclk;
 
 	struct clk_bulk_data clocks[] = {
 		{ .id = "pll" },
@@ -700,9 +699,6 @@ static int aic32x4_setup_clocks(struct snd_soc_component *component,
 	if (ret)
 		return ret;
 
-	mclk = clk_get_parent(clocks[1].clk);
-	mclk_rate = clk_get_rate(mclk);
-
 	if (sample_rate <= 48000) {
 		aosr = 128;
 		adc_resource_class = 6;