linux-wandboard

[SPARC64]: Allow CONFIG_MEMORY_HOTPLUG to build.

online_page() is straightforward, and then add a dummy
remove_memory() that returns -EINVAL just like i386.

There is no point in implementing remove_memory() since
__remove_pages() has no implementation either.

Signed-off-by: David S. Miller <davem@davemloft.net>