x86/smp: Remove single IPI wrapper

All APIC implementation have send_IPI now. Remove the conditional in
the calling code.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Borislav Petkov <bp@alien.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mike Travis <travis@sgi.com>
Cc: Daniel J Blueman <daniel@numascale.com>
Link: http://lkml.kernel.org/r/20151104220849.807817097@linutronix.de

arch/x86/kernel/smp.c

@@ -114,18 +114,6 @@
 static atomic_t stopping_cpu = ATOMIC_INIT(-1);
 static bool smp_no_nmi_ipi = false;
 
-/*
- * Helper wrapper: not all apic definitions support sending to
- * a single CPU, so we fall back to sending to a mask.
- */
-static void send_IPI_cpu(int cpu, int vector)
-{
-	if (apic->send_IPI)
-		apic->send_IPI(cpu, vector);
-	else
-		apic->send_IPI_mask(cpumask_of(cpu), vector);
-}
-
 /*
  * this function sends a 'reschedule' IPI to another CPU.
  * it goes straight through and wastes no time serializing
@@ -137,12 +125,12 @@ static void native_smp_send_reschedule(int cpu)
 		WARN_ON(1);
 		return;
 	}
-	send_IPI_cpu(cpu, RESCHEDULE_VECTOR);
+	apic->send_IPI(cpu, RESCHEDULE_VECTOR);
 }
 
 void native_send_call_func_single_ipi(int cpu)
 {
-	send_IPI_cpu(cpu, CALL_FUNCTION_SINGLE_VECTOR);
+	apic->send_IPI(cpu, CALL_FUNCTION_SINGLE_VECTOR);
 }
 
 void native_send_call_func_ipi(const struct cpumask *mask)