ASoC: SOF: ipc4-topology: don't allocate blob if it will not be used

ASoC: SOF: ipc4-topology: don't allocate blob if it will not be used

A copier blob will be only used when a copier is connected in the
topology. An ALH copier in playback direction that doesn't have any
source means the copier is not connected in the topology. Thus, we
don't need to allocate the blob.
The patch doesn't do the same test before freeing the blob because
the blob is null and it is fine to free null.

Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
Link: https://lore.kernel.org/r/20230307110830.2178-1-peter.ujfalusi@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>