The subwoofer on Inspiron 7559 was disabled originally.
Applying a pin fixup to node 0x1b can enable it and make it work.

Old pin: 0x411111f0
New pin: 0x90170151
Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>