irqchip/armada-370-xp: Fix return value of armada_370_xp_msi_alloc()

IRQ domain alloc function should return zero on success. Non-zero value
indicates failure.
Signed-off-by: Pali Rohár <pali@kernel.org>
Fixes: fcc392d5 ("irqchip/armada-370-xp: Use the generic MSI infrastructure")
Cc: stable@vger.kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20211125130057.26705-1-pali@kernel.org

drivers/irqchip/irq-armada-370-xp.c

@@ -250,7 +250,7 @@ static int armada_370_xp_msi_alloc(struct irq_domain *domain, unsigned int virq,
 				    NULL, NULL);
 	}
 
-	return hwirq;
+	return 0;
 }
 
 static void armada_370_xp_msi_free(struct irq_domain *domain,