x86, NUMA: Enable CONFIG_AMD_NUMA on 32bit too

Now that NUMA init path is unified, amdtopology can be enabled on
32bit.  Make amdtopology.c safe on 32bit by explicitly using u64 and
drop X86_64 dependency from Kconfig.

Inclusion of bootmem.h is added for max_pfn declaration.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>