x86, UV: Fix target_cpus() in x2apic_uv_x.c

target_cpu() should initially target all cpus, not just cpu 0.
Otherwise systems with lots of disks can exhaust the interrupt
vectors on cpu 0 if a large number of disks are discovered
before the irq balancer is running.

Note: UV code only...
Signed-off-by: NJack Steiner <steiner@sgi.com>
LKML-Reference: <20100311184328.GA21433@sgi.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

arch/x86/kernel/apic/x2apic_uv_x.c

@@ -114,11 +114,9 @@ EXPORT_SYMBOL_GPL(uv_possible_blades);
 unsigned long sn_rtc_cycles_per_second;
 EXPORT_SYMBOL(sn_rtc_cycles_per_second);
 
-/* Start with all IRQs pointing to boot CPU.  IRQ balancing will shift them. */
-
 static const struct cpumask *uv_target_cpus(void)
 {
-	return cpumask_of(0);
+	return cpu_online_mask;
 }
 
 static void uv_vector_allocation_domain(int cpu, struct cpumask *retmask)