ALSA: line6: Fix POD sysfs attributes segfault

ALSA: line6: Fix POD sysfs attributes segfault

[ Upstream commit b027d11263836a0cd335520175257dcb99b43757 ]

The commit 02fc76f6a changed base of the sysfs attributes from device to card.
The "show" callbacks dereferenced wrong objects because of this.

Fixes: 02fc76f6a7db ('ALSA: line6: Create sysfs via snd_card_add_dev_attr()')
Cc: <stable@vger.kernel.org> # v4.0+
Reviewed-by: Stefan Hajnoczi <stefanha@gmail.com>
Signed-off-by: Andrej Krutak <dev@andree.sk>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>