[PATCH] memory hotplug: fix compile error for i386 with NUMA config

Fix compile error when config memory hotplug with numa on i386.

The cause of compile error was missing of arch_add_memory(),
remove_memory(), and memory_add_physaddr_to_nid().

Signed-off-by: Yasunori Goto <y-goto@jp.fujitsu.com>
Acked-by: David Rientjes <rientjes@cs.washington.edu>
Acked-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>