fs/file_table.c:fput(): make comment more truthful

Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Andrey Vagin <avagin@openvz.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>