ALSA: hda - Allow to enable/disable vmaster build explicitly

Another preliminary patch for the dual-codec support: since the
support of vmaster over multiple codecs is difficult, simply disable
it by a new flag to hda_codec struct.  A new user hint is added as
well for consistency.

Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/hda/hda_generic.h

@@ -229,6 +229,7 @@ struct hda_gen_spec {
 	unsigned int add_jack_modes:1; /* add i/o jack mode enum ctls */
 	unsigned int power_down_unused:1; /* power down unused widgets */
 	unsigned int dac_min_mute:1; /* minimal = mute for DACs */
+	unsigned int suppress_vmaster:1; /* don't create vmaster kctls */
 
 	/* other internal flags */
 	unsigned int no_analog:1; /* digital I/O only */