ALSA: usb-audio: qcom: clear opened when stream enable fails

ALSA: usb-audio: qcom: clear opened when stream enable fails

On enable, subs->opened is set before the service_interval is validated;
an invalid interval jumps to the response label without clearing it, so
the substream is wedged at -EBUSY until a disable or disconnect.

Clear subs->opened on the enable error path.

Fixes: 326bbc348298a ("ALSA: usb-audio: qcom: Introduce QC USB SND offloading support")
Assisted-by: Claude:claude-opus-4-8
Signed-off-by: Michael Bommarito <michael.bommarito@gmail.com>
Link: https://patch.msgid.link/20260618025126.1862954-3-michael.bommarito@gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>