spapr_pci: Fix interrupt leak in rtas_ibm_change_msi() error path

Now that IRQ allocation has been split in two (first allocate IRQ numbers,
then claim them), if the claiming fails, we must release the IRQs.

Fixes: 4fe75a8 "spapr: split the IRQ allocation sequence"
Signed-off-by: Greg Kurz <groug@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

hw/ppc/spapr_pci.c

@@ -393,6 +393,12 @@ static void rtas_ibm_change_msi(PowerPCCPU *cpu, sPAPRMachineState *spapr,
     for (i = 0; i < req_num; i++) {
         spapr_irq_claim(spapr, irq + i, false, &err);
         if (err) {
+            if (i) {
+                spapr_irq_free(spapr, irq, i);
+            }
+            if (!smc->legacy_irq_allocation) {
+                spapr_irq_msi_free(spapr, irq, req_num);
+            }
             error_reportf_err(err, "Can't allocate MSIs for device %x: ",
                               config_addr);
             rtas_st(rets, 0, RTAS_OUT_HW_ERROR);