ASoC: SOF: Intel: hda-stream: store stream capabilities

Add stream_max into struct sof_intel_hda_dev to store the total hda
stream number that the platform can support, and initialize it at
stream_init.

This can be used later e.g. for stream bitmask.

Signed-off-by: Keyon Jie <yang.jie@linux.intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>