ASoC: wm8994: Allow rate configuration with custom mic callback

If a driver using a custom mic detection callback has provided a table
of mic detection rates via platform data then use it.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
diff --git a/sound/soc/codecs/wm8994.c b/sound/soc/codecs/wm8994.c
index e10d46a..ca6d822 100644
--- a/sound/soc/codecs/wm8994.c
+++ b/sound/soc/codecs/wm8994.c
@@ -82,7 +82,8 @@
 	const struct wm8958_micd_rate *rates;
 	int num_rates;
 
-	if (wm8994->jack_cb != wm8958_default_micdet)
+	if (!(wm8994->pdata && wm8994->pdata->micd_rates) &&
+	    wm8994->jack_cb != wm8958_default_micdet)
 		return;
 
 	idle = !wm8994->jack_mic;