x86-64, NUMA: Emulate directly from numa_meminfo

NUMA emulation built physnodes[] array which could only represent
configurations from the physical meminfo and emulated nodes using the
information.  There's no reason to take this extra level of
indirection.  Update emulation functions so that they operate directly
on numa_meminfo.  This simplifies the code and makes emulation layout
behave better with interleaved physical nodes.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Shaohui Zheng <shaohui.zheng@intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: H. Peter Anvin <hpa@linux.intel.com>