Commit 5dabfc78 ("ext4: rename {exit,init}_ext4_*() to
ext4_{exit,init}_*()") causes

  fs/ext4/super.c:4776: error: implicit declaration of function ‘ext4_init_xattr’

when CONFIG_EXT4_FS_XATTR is disabled.

It renamed init_ext4_xattr to ext4_init_xattr but forgot to update the
dummy definition in fs/ext4/xattr.h.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Acked-by: N"Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>