ALSA: cmi8330: add MPU-401 support

Add MPU-401 port support for the chip.
Also, update some error messages and description.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/isa/Kconfig b/sound/isa/Kconfig
index be2d377..5915dc4 100644
--- a/sound/isa/Kconfig
+++ b/sound/isa/Kconfig
@@ -95,6 +95,7 @@
 	select SND_WSS_LIB
 	select SND_SB16_DSP
 	select SND_OPL3_LIB
+	select SND_MPU401_UART
 	help
 	  Say Y here to include support for soundcards based on the
 	  C-Media CMI8330 chip.