[POWERPC] mpic_pasemi_msi: 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 <[e-mail]>
Signed-off-by: Paul Mackerras <[e-mail]>

arch/powerpc/sysdev/mpic_pasemi_msi.c

···
 	unsigned int virq;
 	struct msi_desc *entry;
 	struct msi_msg msg;
+	int ret;
 
 	pr_debug("pasemi_msi_setup_msi_irqs, pdev %p nvec %d type %d\n",
 		 pdev, nvec, type);
···
 		 * few MSIs for someone, but restrictions will apply to how the
 		 * sources can be changed independently.
 		 */
-		hwirq = mpic_msi_alloc_hwirqs(msi_mpic, ALLOC_CHUNK);
-		if (hwirq < 0) {
+		ret = mpic_msi_alloc_hwirqs(msi_mpic, ALLOC_CHUNK);
+		hwirq = ret;
+		if (ret < 0) {
 			pr_debug("pasemi_msi: failed allocating hwirq\n");
 			return hwirq;
 		}