mfd: ucb1400 sound driver uses/depends on AC97_BUS:

ERROR: "ac97_bus_type" [drivers/mfd/ucb1400_core.ko] undefined!
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Samuel Ortiz <sameo@openedhand.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

drivers/mfd/Kconfig

@@ -52,6 +52,7 @@ config HTC_PASIC3
 
 config UCB1400_CORE
 	tristate "Philips UCB1400 Core driver"
+	depends on AC97_BUS
 	help
 	  This enables support for the Philips UCB1400 core functions.
 	  The UCB1400 is an AC97 audio codec.