move drivers/mfd/*.h to include/linux/mfd

So drivers like collie_battery driver can use
those files easier.
diff --git a/drivers/mfd/ucb1x00-ts.c b/drivers/mfd/ucb1x00-ts.c
index 61b7d3e..000cb41 100644
--- a/drivers/mfd/ucb1x00-ts.c
+++ b/drivers/mfd/ucb1x00-ts.c
@@ -30,12 +30,12 @@
 #include <linux/freezer.h>
 #include <linux/slab.h>
 #include <linux/kthread.h>
+#include <linux/mfd/ucb1x00.h>
 
 #include <mach/dma.h>
 #include <mach/collie.h>
 #include <asm/mach-types.h>
 
-#include "ucb1x00.h"
 
 
 struct ucb1x00_ts {