powerpc: Fix irq_set_affinity() return values

Signed-off-by: Alexander Gordeev <agordeev@redhat.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/arch/powerpc/sysdev/xics/ics-opal.c b/arch/powerpc/sysdev/xics/ics-opal.c
index f7e8609..39d7221 100644
--- a/arch/powerpc/sysdev/xics/ics-opal.c
+++ b/arch/powerpc/sysdev/xics/ics-opal.c
@@ -148,7 +148,7 @@
 		       __func__, d->irq, hw_irq, server, rc);
 		return -1;
 	}
-	return 0;
+	return IRQ_SET_MASK_OK;
 }
 
 static struct irq_chip ics_opal_irq_chip = {