ARC: [SMP] IPI ACK interface doesn't need "self" cpu-id

The interface is confusing, it feels like we are getting "sender" info,
whereas it is the "receiver", which can very well be retrived by
smp_processor_id(), if need be.

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
diff --git a/arch/arc/plat-arcfpga/smp.c b/arch/arc/plat-arcfpga/smp.c
index 5e4fe95..8a12741 100644
--- a/arch/arc/plat-arcfpga/smp.c
+++ b/arch/arc/plat-arcfpga/smp.c
@@ -93,9 +93,9 @@
 	idu_irq_assert(cpu);
 }
 
-static void iss_model_ipi_clear(int cpu, int irq)
+static void iss_model_ipi_clear(int irq)
 {
-	idu_irq_clear(IDU_INTERRUPT_0 + cpu);
+	idu_irq_clear(IDU_INTERRUPT_0 + smp_processor_id());
 }
 
 void iss_model_init_early_smp(void)