ASoC: fsl_micfil: simplify clock setting

ASoC: fsl_micfil: simplify clock setting

The reference manual has this for calculating the micfil internal clock
divider:

         MICFIL Clock rate
clkdiv = -----------------
         8 * OSR * outrate

(with OSR == Oversampling Rate, outrate == output sample rate)

The driver first sets the MICFIL Clock rate to (outrate * 1024) and then
calculates back the clkdiv value from the above calculation.

Simplify this by using a fixed clkdiv value of 8 and set the MICFIL
Clock rate to (outrate * clkdiv * OSR * 8).

While at it drop disabling the clock before setting its rate. The MICFIL
module is disabled when the rate is changed and it is also resetted
before it is started again, so I doubt it's necessary to disable the
clock.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Acked-by: Shengjiu Wang <shengjiu.wang@gmail.com>
Link: https://lore.kernel.org/r/20220414162249.3934543-16-s.hauer@pengutronix.de
Signed-off-by: Mark Brown <broonie@kernel.org>