ASoC: soc-pcm: fix checks for multi-cpu FE dailinks

soc_dpcm_fe_runtime_update() is called for all dailinks, and we want
to first discard all back-ends, then deal with front-ends.

The existing code first reports an error with multi-cpu front-ends,
and that check needs to be moved after we know that we are dealing
with a front-end.

Fixes: 6e1276a5 ('ASoC: Return error if the function does not support multi-cpu')
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Reviewed-by: Bard Liao <yung-chuan.liao@linux.intel.com>
BugLink: https://github.com/thesofproject/linux/issues/1970
Link: https://lore.kernel.org/r/20200612203507.25621-1-pierre-louis.bossart@linux.intel.com


Signed-off-by: Mark Brown <broonie@kernel.org>