don't need that forward declaration of struct nameidata in dcache.h anymore

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index 27a7f00..b2a2a08 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -11,7 +11,6 @@
 #include <linux/rcupdate.h>
 #include <linux/lockref.h>
 
-struct nameidata;
 struct path;
 struct vfsmount;