Add helper matching allocation done in hda_bus_ml_get_capabilities().

No functionality change, just clearer code partitioning.
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Rander Wang <rander.wang@intel.com>
Reviewed-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Reviewed-by: Péter Ujfalusi <peter.ujfalusi@linux.intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Link: https://lore.kernel.org/r/20221027193540.259520-19-pierre-louis.bossart@linux.intel.comSigned-off-by: Mark Brown <broonie@kernel.org>