ASoC: soc-pcm: fix dpcm_path_get error handling

dpcm_path_get may return -ENOMEM when allocating memory for list
fails. We should not keep processing path or start up dpcm dai in
this case.

Signed-off-by: Qiao Zhou <zhouqiao@marvell.com>
Acked-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>