ASoC: SOF: compress: fix null check after dereference

ASoC: SOF: compress: fix null check after dereference

"cstream" is dereferenced but null checked later. Swap their
positions to avoid potential null dereference.

Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Reviewed-by: Daniel Baluta <daniel.baluta@nxp.com>
Reviewed-by: Péter Ujfalusi <peter.ujfalusi@linux.intel.com>
Signed-off-by: Weiguo Li <liwg06@foxmail.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20220310171651.249385-3-pierre-louis.bossart@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>