ALSA: hda - Fix oops caused by recent commit "Fix internal mic for Lenovo Ideapad U300s"

Make sure we don't dereference the "quirk" pointer when it is null.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David Henningsson <david.henningsson@canonical.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>