ASoC: core: only flush inited work during free

There are many paths to soc_free_pcm_runtime which can both have and
have not yet inited the workqueue yet. When we flush the queue when we
have not yet inited the queue we cause warnings to be printed.

An example is soc_cleanup_card_resources which is called by
snd_soc_bind_card which has multiple failure points before and after
soc_link_init -> soc_new_pcm which is where the queue is inited.

Signed-off-by: Curtis Malainey <cujomalainey@chromium.org>
Link: https://lore.kernel.org/r/20191128011358.39234-1-cujomalainey@chromium.org


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