m68k/mac: Fix mac_irq_pending() for PSC MACE and SCC

Add missing return statement. The docs say that the level 4 PSC IRQs
relate to MACE DMA and SCC. Since those drivers don't call
mac_irq_pending() this patch has no affect. But it should be fixed all the
same, since it can be useful for MACE debugging.
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Signed-off-by: NGeert Uytterhoeven <geert@linux-m68k.org>

arch/m68k/mac/macints.c

@@ -370,7 +370,7 @@ int mac_irq_pending(unsigned int irq)
 		break;
 	case 4:
 		if (psc_present)
-			psc_irq_pending(irq);
+			return psc_irq_pending(irq);
 		break;
 	}
 	return 0;