ALSA: hda - Add mic mute hotkey quirk for Lenovo ThinkCentre AIO

The Lenovo ThinkCenter AIO uses Line2 (NID 0x1b) to implement the
micmute hotkey, here we register an input device and use Line2 unsol
event to collect the hotkey pressing or releasing.

In the meanwhile, the micmute led is controlled by GPIO2, so we
use an existing function alc_fixup_gpio_mic_mute_hook() to control
the led.

[Hui: And there are two places to register the input device, to make
the code simple and clean, move the two same code sections into a
function.]

Cc: <stable@vger.kernel.org>
Signed-off-by: Kailang <kailang@realtek.com>
Signed-off-by: Hui Wang <hui.wang@canonical.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>