[PATCH] Documentation: remount_fs() needs lock_kernel

Fixed long-lived typo: remount_fs() needs BKL

Signed-off-by: Vasily Averin <vvs@sw.ru>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>