ASoC: arizona: Add support for 768kHz DMIC operation

The new IPs supports a new lower frequency 768kHz DMIC operation
add support for this into the OSR control.
Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/arizona.c

@@ -648,7 +648,7 @@ SOC_ENUM_SINGLE_DECL(arizona_in_hpf_cut_enum,
 EXPORT_SYMBOL_GPL(arizona_in_hpf_cut_enum);
 
 static const char * const arizona_in_dmic_osr_text[] = {
-	"1.536MHz", "3.072MHz", "6.144MHz",
+	"1.536MHz", "3.072MHz", "6.144MHz", "768kHz",
 };
 
 const struct soc_enum arizona_in_dmic_osr[] = {