Add missing masking of sched domain span

The cpus of the physical node are not properly masked by the cpumap like
the other levels of sched domains.

Add the missing mask.

Signed-off-by: Christoph Lameter <clameter@sgi.com>

Index: linux-2.6.20-rc5/kernel/sched.c
===================================================================
--- linux-2.6.20-rc5.orig/kernel/sched.c	2007-01-12 12:54:26.000000000 -0600
+++ linux-2.6.20-rc5/kernel/sched.c	2007-01-23 19:22:56.266686337 -0600
@@ -6496,6 +6496,7 @@ static int build_sched_domains(const cpu
 		sd->parent = p;
 		if (p)
 			p->child = sd;
+		cpus_and(sd->span, sd->span, *cpu_map);
 		cpu_to_phys_group(i, cpu_map, &sd->groups);
 
 #ifdef CONFIG_SCHED_MC