ASoC: fsl_micfil: Correct the number of steps on SX controls

The parameter "max" of SOC_SINGLE_SX_TLV() means the number of steps
rather than maximum value. This patch corrects the minimum value to -8
and the number of steps to 15.

Signed-off-by: Chancel Liu <chancel.liu@nxp.com>
Acked-by: Shengjiu Wang <shengjiu.wang@gmail.com>
Link: https://lore.kernel.org/r/20230104025754.3019235-1-chancel.liu@nxp.com


Signed-off-by: Mark Brown <broonie@kernel.org>