ASoC: Intel: hsw_rt5640: Improve probe() function quality

Declare local 'dev' and make use of it plus dev_get_platdata() to
improve code readability.

Signed-off-by: Cezary Rojewski <cezary.rojewski@intel.com>
Reviewed-by: Amadeusz Sławiński <amadeuszx.slawinski@linux.intel.com>
Tested-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20220620101402.2684366-7-cezary.rojewski@intel.com


Signed-off-by: Mark Brown <broonie@kernel.org>