ASoC: sta32x: Optimize the array work to find rate_min and rate_max

For a given ir and fs, there is at most one possible match for the case
mclk_ratios[ir][j].ratio * fs == freq.
Thus we can break from the inner loop once a match is found.

Signed-off-by: Axel Lin <axel.lin@gmail.com>
Acked-by: Johannes Stezenbach <js@sig21.net>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>