ALSA: hda - Check the existing path in snd_hda_add_new_path()

If the requested path has been already added, return the existing path
instance instead of adding a duplicated instance.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/pci/hda/hda_generic.h b/sound/pci/hda/hda_generic.h
index 1090a52..f1cae2e 100644
--- a/sound/pci/hda/hda_generic.h
+++ b/sound/pci/hda/hda_generic.h
@@ -53,6 +53,7 @@
 	unsigned char multi[MAX_NID_PATH_DEPTH];
 	unsigned int ctls[NID_PATH_NUM_CTLS]; /* NID_PATH_XXX_CTL */
 	bool active;
+	bool with_aa_mix;
 };
 
 /* mic/line-in auto switching entry */