ASoC: wcd9310: Return on an invalid switch value

In tabla_get_mbhc_micbias_regs the switch statement for the calibration
bias should never get to the default clause, but if it does return out
of the function and avoid a possible compiler warning.

Change-Id: Ic0dedbadf889a8e4ef9de0a906da0f97bc0f6a6d
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>
diff --git a/sound/soc/codecs/wcd9310.c b/sound/soc/codecs/wcd9310.c
index 5003ab5..bf72b11 100644
--- a/sound/soc/codecs/wcd9310.c
+++ b/sound/soc/codecs/wcd9310.c
@@ -1717,6 +1717,7 @@
 	default:
 		/* Should never reach here */
 		pr_err("%s: Invalid MIC BIAS for MBHC\n", __func__);
+		return;
 	}
 
 	micbias_regs->cfilt_sel = cfilt;