apparmor: remove duplicate macro list_entry_is_head()

Strangely I hadn't had noticed the existence of the list_entry_is_head()
in apparmor code when added the same one in the list.h.  Luckily it's
fully identical and didn't break builds.  In any case we don't need a
duplicate anymore, thus remove it from apparmor code.

Link: https://lkml.kernel.org/r/20201208100639.88182-1-andriy.shevchenko@linux.intel.com
Fixes: e130816 ("include/linux/list.h: add a macro to test if entry is pointing to the head")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: John Johansen <john.johansen@canonical.com>
Cc: James Morris <jmorris@namei.org>
Cc: "Serge E . Hallyn " <serge@hallyn.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

security/apparmor/apparmorfs.c

@@ -2046,9 +2046,6 @@ int __aafs_ns_mkdir(struct aa_ns *ns, struct dentry *parent, const char *name,
 	return error;
 }
 
-
-#define list_entry_is_head(pos, head, member) (&pos->member == (head))
-
 /**
  * __next_ns - find the next namespace to list
  * @root: root namespace to stop search at (NOT NULL)