ALSA: line6: Fix wrong altsetting for LINE6_PODHD500_1

Commit 7b9584fa ("staging: line6: Move altsetting to properties")
set a wrong altsetting for LINE6_PODHD500_1 during refactoring.

Set the correct altsetting number to fix the issue.

BugLink: https://bugs.launchpad.net/bugs/1790595
Fixes: 7b9584fa

 ("staging: line6: Move altsetting to properties")
Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>