ASoC: codecs: rt1308-sdw: remove duplicate allocation

ASoC: codecs: rt1308-sdw: remove duplicate allocation

The .read_prop callback is supposed to be called by the SoundWire core
only. Calling it again from this driver results in an additional
memory allocation for no good reason.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
Reviewed-by: Rander Wang <rander.wang@intel.com>
Cc: Oder Chiou <oder_chiou@realtek.com>
Cc: Shuming Fan <shumingf@realtek.com>
Cc: Jack Yu <jack.yu@realtek.com>
Link: https://lore.kernel.org/r/20200515211531.11416-4-pierre-louis.bossart@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>