ASoC: fsl_sai: Revert "ASoC: fsl_sai: Enable MCTL_MCLK_EN bit for master mode"

This reverts commit ff87d619.

Andreas reports that on an i.MX8MP-based system where MCLK needs to be
used as an input, the MCLK pin is actually an output, despite not having
the 'fsl,sai-mclk-direction-output' property present in the devicetree.

This is caused by commit ff87d619 ("ASoC: fsl_sai: Enable
MCTL_MCLK_EN bit for master mode") that sets FSL_SAI_MCTL_MCLK_EN
unconditionally for imx8mm/8mn/8mp/93, causing the MCLK to always
be configured as output.

FSL_SAI_MCTL_MCLK_EN corresponds to the MOE (MCLK Output Enable) bit
of register MCR and the drivers sets it when the
'fsl,sai-mclk-direction-output' devicetree property is present.

Revert the commit to allow SAI to use MCLK as input as well.

Cc: stable@vger.kernel.org
Fixes: ff87d619 ("ASoC: fsl_sai: Enable MCTL_MCLK_EN bit for master mode")
Reported-by: Andreas Henriksson <andreas@fatal.se>
Signed-off-by: Fabio Estevam <festevam@denx.de>
Acked-by: Shengjiu Wang <shengjiu.wang@gmail.com>
Link: https://lore.kernel.org/r/20230706221827.1938990-1-festevam@gmail.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/fsl/fsl_sai.c

@@ -507,12 +507,6 @@ static int fsl_sai_set_bclk(struct snd_soc_dai *dai, bool tx, u32 freq)
 				   savediv / 2 - 1);
 	}
 
-	if (sai->soc_data->max_register >= FSL_SAI_MCTL) {
-		/* SAI is in master mode at this point, so enable MCLK */
-		regmap_update_bits(sai->regmap, FSL_SAI_MCTL,
-				   FSL_SAI_MCTL_MCLK_EN, FSL_SAI_MCTL_MCLK_EN);
-	}
-
 	return 0;
 }