ASoC: soc-pcm: Fix an uninitialized error code

The error path here doesn't set "ret" so it returns uninitialized data
instead of a negative error code.

Fixes: 2c138284

 ("ASoC: soc-pcm: disconnect BEs if the FE is not ready")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: https://lore.kernel.org/r/X/wfXQFxeMLvpO+1@mwanda
Signed-off-by: Mark Brown <broonie@kernel.org>