kernel/user.c: drop unused field 'files' from user_struct

Nobody seems uses it for a long time. Let's drop it.
Signed-off-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

include/linux/sched.h

@@ -745,7 +745,6 @@ static inline int signal_group_exit(const struct signal_struct *sig)
 struct user_struct {
 	atomic_t __count;	/* reference count */
 	atomic_t processes;	/* How many processes does this user have? */
-	atomic_t files;		/* How many open files does this user have? */
 	atomic_t sigpending;	/* How many pending signals does this user have? */
 #ifdef CONFIG_INOTIFY_USER
 	atomic_t inotify_watches; /* How many inotify watches does this user have? */

kernel/user.c

@@ -87,7 +87,6 @@ static DEFINE_SPINLOCK(uidhash_lock);
 struct user_struct root_user = {
 	.__count	= ATOMIC_INIT(1),
 	.processes	= ATOMIC_INIT(1),
-	.files		= ATOMIC_INIT(0),
 	.sigpending	= ATOMIC_INIT(0),
 	.locked_shm     = 0,
 	.uid		= GLOBAL_ROOT_UID,