ASoC: wm8974: remove unused variables

sound/soc/codecs/wm8974.c:200:38: warning:
 wm8974_aux_boost_controls defined but not used [-Wunused-const-variable=]
sound/soc/codecs/wm8974.c:204:38: warning:
 wm8974_mic_boost_controls defined but not used [-Wunused-const-variable=]

commit 8a123ee2 ("ASoC: WM8974 DAPM cleanups")
left behind this, remove them.
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Link: https://lore.kernel.org/r/20200324070615.16248-1-yuehaibing@huawei.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/wm8974.c

@@ -196,14 +196,6 @@ SOC_DAPM_SINGLE("MicN Switch", WM8974_INPUT, 1, 1, 0),
 SOC_DAPM_SINGLE("MicP Switch", WM8974_INPUT, 0, 1, 0),
 };
 
-/* AUX Input boost vol */
-static const struct snd_kcontrol_new wm8974_aux_boost_controls =
-SOC_DAPM_SINGLE("Aux Volume", WM8974_ADCBOOST, 0, 7, 0);
-
-/* Mic Input boost vol */
-static const struct snd_kcontrol_new wm8974_mic_boost_controls =
-SOC_DAPM_SINGLE("Mic Volume", WM8974_ADCBOOST, 4, 7, 0);
-
 static const struct snd_soc_dapm_widget wm8974_dapm_widgets[] = {
 SND_SOC_DAPM_MIXER("Speaker Mixer", WM8974_POWER3, 2, 0,
 	&wm8974_speaker_mixer_controls[0],