ALSA: drivers: opl3: Fix incorrect use of vp->state

ALSA: drivers: opl3: Fix incorrect use of vp->state

Static analysis with scan-build has found an assignment to vp2 that is
never used. It seems that the check on vp->state > 0 should be actually
on vp2->state instead. Fix this.

This dates back to 2002, I found the offending commit from the git
history git://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git,
commit 91e39521bbf6 ("[PATCH] ALSA patch for 2.5.4")

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20211212172025.470367-1-colin.i.king@gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>