[POWERPC] mpic_u3msi: Failed allocation unnoticed

bitmap_find_free_region(), called by mpic_msi_alloc_hwirqs() may return
signed, but hwirq is unsigned.  A failed allocation remains unnoticed.

Signed-off-by: Roel Kluin <12o3l@tiscali.nl>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/sysdev/mpic_u3msi.c

@@ -115,17 +115,19 @@ static int u3msi_setup_msi_irqs(struct pci_dev *pdev, int nvec, int type)
 	struct msi_desc *entry;
 	struct msi_msg msg;
 	u64 addr;
+	int ret;
 
 	addr = find_ht_magic_addr(pdev);
 	msg.address_lo = addr & 0xFFFFFFFF;
 	msg.address_hi = addr >> 32;
 
 	list_for_each_entry(entry, &pdev->msi_list, list) {
-		hwirq = mpic_msi_alloc_hwirqs(msi_mpic, 1);
-		if (hwirq < 0) {
+		ret = mpic_msi_alloc_hwirqs(msi_mpic, 1);
+		if (ret < 0) {
 			pr_debug("u3msi: failed allocating hwirq\n");
-			return hwirq;
+			return ret;
 		}
+		hwirq = ret;
 
 		virq = irq_create_mapping(msi_mpic->irqhost, hwirq);
 		if (virq == NO_IRQ) {