ASoC: dapm: Potential small memory leak in dapm_cnew_widget()

We should free "w" on the error path.

Fixes: 199ed3e8 ("ASoC: dapm: fix use-after-free issue with dailink sname")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Mark Brown <broonie@kernel.org>