[SPARC64]: Add SMT scheduling support for Niagara.

The mapping is a simple "(cpuid >> 2) == core" for now.
Later we'll add more sophisticated code that will walk
the sun4v machine description and figure this out from
there.

We should also add core mappings for jaguar and panther
processors.

Signed-off-by: David S. Miller <davem@davemloft.net>

include/asm-sparc64/smp.h

@@ -33,6 +33,8 @@
 extern cpumask_t phys_cpu_present_map;
 #define cpu_possible_map phys_cpu_present_map
 
+extern cpumask_t cpu_sibling_map[NR_CPUS];
+
 /*
  *	General functions that each host system must provide.
  */