ASoC: dapm: dapm_dai_get_connected_widgets: Fix missing mutex unlock

Make sure to unlock the DAPM mutex when dapm_widget_list_create() fails.

This means the function will now generate a trace_snd_soc_dapm_connected
event, even if the creation of the list fails. But that was the behavior
before the patch that introduced the unlock issue, so that should be fine.

Fixes: 1ce43acf ("ASoC: dapm: Simplify list creation in dapm_dai_get_connected_widgets()")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@kernel.org>