ALSA: Fix leftover chmap UNKNOWN -> MONO conversions

A few files have been slipped from the previous commit to add MONO
channel type.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/pci/ymfpci/ymfpci_main.c b/sound/pci/ymfpci/ymfpci_main.c
index 50b0804..3a6f03f 100644
--- a/sound/pci/ymfpci/ymfpci_main.c
+++ b/sound/pci/ymfpci/ymfpci_main.c
@@ -1264,7 +1264,7 @@
 
 static const struct snd_pcm_chmap_elem surround_map[] = {
 	{ .channels = 1,
-	  .map = { SNDRV_CHMAP_UNKNOWN } },
+	  .map = { SNDRV_CHMAP_MONO } },
 	{ .channels = 2,
 	  .map = { SNDRV_CHMAP_RL, SNDRV_CHMAP_RR } },
 	{ }