ALSA: hda - Add a flag to suppress mic auto-switch

Add a new flag spec->suppress_mic_auto_switch for codecs that don't
support unsol events properly like VT1708.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/pci/hda/hda_generic.c b/sound/pci/hda/hda_generic.c
index 8e7ce7d..b488c62 100644
--- a/sound/pci/hda/hda_generic.c
+++ b/sound/pci/hda/hda_generic.c
@@ -3034,6 +3034,9 @@
 	unsigned int types;
 	int i, num_pins;
 
+	if (spec->suppress_auto_mic)
+		return 0;
+
 	types = 0;
 	num_pins = 0;
 	for (i = 0; i < cfg->num_inputs; i++) {