[IA64] Cleanup use of various #defines related to nodes

Some of the SN code & #defines related to compact nodes & IO discovery
have gotten stale over the years. This patch attempts to clean them up.
Some of the various SN MAX_xxx #defines were also unclear & misused.

The primary changes are:

	- use MAX_NUMNODES. This is the generic linux #define for the number
	  of nodes that are known to the generic kernel. Arrays & loops
	  for constructs that are 1:1 with linux-defined nodes should
	  use the linux #define - not an SN equivalent.

	- use MAX_COMPACT_NODES for MAX_NUMNODES + NUM_TIOS. This is the
	  number of nodes in the SSI system. Compact nodes are a hack to
	  get around the IA64 architectural limit of 256 nodes. Large SGI
	  systems have more than 256 nodes. When we upgrade to ACPI3.0,
	  I _hope_ that all nodes will be real nodes that are known to
	  the generic kernel. That will allow us to delete the notion
	  of "compact nodes".

	- add MAX_NUMALINK_NODES for the total number of nodes that
	  are in the numalink domain - all partitions.

	- simplified (understandable) scan_for_ionodes()

	- small amount of cleanup related to cnodes

Signed-off-by: Jack Steiner <steiner@sgi.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
diff --git a/include/asm-ia64/sn/io.h b/include/asm-ia64/sn/io.h
index 4220973..ac30c74 100644
--- a/include/asm-ia64/sn/io.h
+++ b/include/asm-ia64/sn/io.h
@@ -14,7 +14,7 @@
 extern void * sn_io_addr(unsigned long port) __attribute_const__; /* Forward definition */
 extern void __sn_mmiowb(void); /* Forward definition */
 
-extern int numionodes;
+extern int num_cnodes;
 
 #define __sn_mf_a()   ia64_mfa()