ALSA: hda/realtek - Add headset mode support for Dell laptop

This platform had two Dmic and single Dmic.
This update was for single Dmic.

This commit was for two Dmic.

Fixes: 75ee94b2

 ("ALSA: hda - fix headset mic problem for Dell machines...")
Signed-off-by: Kailang Yang <kailang@realtek.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>