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/mpic.c b/arch/powerpc/sysdev/mpic.c
index ee21b5e..0a13ecb 100644
--- a/arch/powerpc/sysdev/mpic.c
+++ b/arch/powerpc/sysdev/mpic.c
@@ -836,7 +836,7 @@
 			       mpic_physmask(mask));
 	}
 
-	return 0;
+	return IRQ_SET_MASK_OK;
 }
 
 static unsigned int mpic_type_to_vecpri(struct mpic *mpic, unsigned int type)