ASoC: arizona: Do not test ratio zero as it is not a valid setting

Zero is not a valid FRATIO for the FLL, as such we shouldn't test it
whilst refining the FRATIO. This patch does just that.
Reported-by: Ryo Tsutsui <ryo.tsutsui@wolfsonmicro.com>
Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

sound/soc/codecs/arizona.c

@@ -1585,7 +1585,7 @@ static int arizona_calc_fratio(struct arizona_fll *fll,
 			}
 		}
 
-		for (ratio = init_ratio - 1; ratio >= 0; ratio--) {
+		for (ratio = init_ratio - 1; ratio > 0; ratio--) {
 			if (ARIZONA_FLL_VCO_CORNER / (fll->vco_mult * ratio) <
 			    Fref)
 				break;