x86: fix early cpu_to_node panic from nr_free_zone_pages

call early_cpu_to_node() since per_cpu(cpu_to_node_map) might not be setup
yet.

I also had to export x86_cpu_to_node_map_early_ptr because of some calls
from the network code to numa_node_id():

	net/ipv4/netfilter/arp_tables.c:
	net/ipv4/netfilter/ip_tables.c:
	net/ipv4/netfilter/ip_tables.c:

Signed-off-by: Mike Travis <travis@sgi.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>