ASoC: rockchip: pdm: fix regmap_ops hang issue

This is because set_fmt ops maybe called when PD is off,
and in such case, regmap_ops will lead system hang.
enale PD before doing regmap_ops.

Signed-off-by: Sugar Zhang <sugar.zhang@rock-chips.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/rockchip/rockchip_pdm.c

@@ -208,7 +208,9 @@ static int rockchip_pdm_set_fmt(struct snd_soc_dai *cpu_dai,
 		return -EINVAL;
 	}
 
+	pm_runtime_get_sync(cpu_dai->dev);
 	regmap_update_bits(pdm->regmap, PDM_CLK_CTRL, mask, val);
+	pm_runtime_put(cpu_dai->dev);
 
 	return 0;
 }