helpers for acl caching + switch to those

helpers: get_cached_acl(inode, type), set_cached_acl(inode, type, acl),
forget_cached_acl(inode, type).

ubifs/xattr.c needed includes reordered, the rest is a plain switchover.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/ubifs/xattr.c

@@ -55,9 +55,9 @@
  * ACL support is not implemented.
  */
 
+#include "ubifs.h"
 #include <linux/xattr.h>
 #include <linux/posix_acl_xattr.h>
-#include "ubifs.h"
 
 /*
  * Limit the number of extended attributes per inode so that the total size