ASoC: fsl_sai: Enable MCTL_MCLK_EN bit for master mode

On i.MX8MM, the MCTL_MCLK_EN bit it is not only the gate
for MCLK output to PAD, but also the gate bit between
root clock and SAI module, So it is need to be enabled
for master mode, otherwise there is no bclk generated.

Signed-off-by: Shengjiu Wang <shengjiu.wang@nxp.com>
Link: https://lore.kernel.org/r/1652963808-14515-1-git-send-email-shengjiu.wang@nxp.com
Signed-off-by: Mark Brown <broonie@kernel.org>