getname_kernel() needs to make sure that ->name != ->iname in long case

commit 30ce4d1903e1d8a7ccd110860a5eef3c638ed8be upstream.

missed it in "kill struct filename.separate" several years ago.

Cc: stable@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>