ASoC: SOF: Intel: hda: Simplify error handling during FW boot

Modify cl_stream_prepare() to return a pointer to the prepared stream
if successful or ERR_PTR() otherwise. This would simplify the error
paths in hda_dsp_cl_boot_firmware() and hda_dsp_cl_boot_firmware_iccmax()
to perform the stream cleanup after FW boot. This change also renders
the function get_stream_with_tag() redundant.

Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
Signed-off-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Link: https://lore.kernel.org/r/20200826184532.1612070-9-ranjani.sridharan@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>