ALSA: ua101: Fix unlocked snd_pcm_stop() call

commit 9538aa46c2427d6782aa10036c4da4c541605e0e upstream.

snd_pcm_stop() must be called in the PCM substream lock context.

Acked-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>