ipcns: remove useless get/put while CLONE_NEWIPC

copy_ipcs() doesn't actually copy anything. If new ipcns is created, it's
created from scratch, in this case get/put on old ipcns isn't needed.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Reviewed-by: WANG Cong <xiyou.wangcong@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>