s390/numa: remove superfluous ARCH_WANT defines

The NUMA system call "__ARCH_WANT" defines are not used by the
Linux kernel, therefore remove them.

Fixes: 9df62adffeb0 ("s390/numa: add core infrastructure")
Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>