powerpc/smp: No need to set_need_resched when getting a resched IPI

The comment in the code was asking "Do we have to do this?", and according
to x86 and s390 the answer is no, the scheduler will do it before calling
the arch hook.
Signed-off-by: NMilton Miller <miltonm@bga.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/kernel/smp.c

@@ -101,8 +101,7 @@ void smp_message_recv(int msg)
 		generic_smp_call_function_interrupt();
 		break;
 	case PPC_MSG_RESCHEDULE:
-		/* XXX Do we have to do this? */
-		set_need_resched();
+		/* we notice need_resched on exit */
 		break;
 	case PPC_MSG_CALL_FUNC_SINGLE:
 		generic_smp_call_function_single_interrupt();