ALSA: hda - Fix a failure of micmute led when having multi adcs

On a Dell laptop, there is no global adcs for all input devices, so
the input devices use the different adc, as a result, dyn_adc_switch
is set to true.

In this situation, it is safe to control the micmute led according to
user's choice of muting/unmuting the current input device, since only
current input device path is active, while other input device paths
are inactive and powered down.

Fixes: 00ef9940 ('ALSA: hda - add mic mute led hook for dell machines')
Cc: <stable@vger.kernel.org>
Signed-off-by: Hui Wang <hui.wang@canonical.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>