ALSA: core: remove redundant spin_lock pair in snd_card_disconnect

modification in commit 2a3f7221 ("ALSA: core: Fix card races between
register and disconnect") resulting in this problem.

Fixes: 2a3f7221 ("ALSA: core: Fix card races between register and disconnect")
Signed-off-by: Jia Zhou <zhou.jia2@zte.com.cn>
Signed-off-by: Yi Wang <wang.yi59@zte.com.cn>
Link: https://lore.kernel.org/r/1616989007-34429-1-git-send-email-wang.yi59@zte.com.cn


Signed-off-by: Takashi Iwai <tiwai@suse.de>