x86/uv: update SCIR driver to use the idle_cpu() function

Impact: cleanup

Change UV heartbeat function to use idle_cpu to determine cpu's
"idleness".  Realign uv_hub definitions.
Signed-of-by: Mike Travis <travis@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/genx2apic_uv_x.c

@@ -370,8 +370,8 @@ static void uv_heartbeat(unsigned long ignored)
 	/* flip heartbeat bit */
 	bits ^= SCIR_CPU_HEARTBEAT;
 
-	/* are we the idle thread? */
-	if (current->pid == 0)
+	/* is this cpu idle? */
+	if (idle_cpu(raw_smp_processor_id()))
 		bits &= ~SCIR_CPU_ACTIVITY;
 	else
 		bits |= SCIR_CPU_ACTIVITY;