ASoC: SOF: imx: Replace sdev->private with sdev->pdata->hw_pdata

ASoC: SOF: imx: Replace sdev->private with sdev->pdata->hw_pdata

The correct way to save private data is to use sdev->pdata->hw_pdata.
Removed superfluous type-casts.

Signed-off-by: Iulian Olaru <iulianolaru249@yahoo.com>
Reviewed-by: Daniel Baluta <daniel.baluta@gmail.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Link: https://lore.kernel.org/r/20200825235040.1586478-7-ranjani.sridharan@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>