qemu: fix resource leak

Error: RESOURCE_LEAK:
/libvirt/src/qemu/qemu_driver.c:6968:
alloc_fn: Calling allocation function "calloc".
/libvirt/src/qemu/qemu_driver.c:6968:
var_assign: Assigning: "nodeset" =  storage returned from "calloc(1UL, 1UL)".
/libvirt/src/qemu/qemu_driver.c:6977:
noescape: Variable "nodeset" is not freed or pointed-to in function "virTypedParameterAssign".
/libvirt/src/qemu/qemu_driver.c:6997:
leaked_storage: Variable "nodeset" going out of scope leaks the storage it points to.

src/qemu/qemu_driver.c

@@ -6991,6 +6991,9 @@ qemuDomainGetNumaParameters(virDomainPtr dom,
             if (virTypedParameterAssign(param, VIR_DOMAIN_NUMA_NODESET,
                                         VIR_TYPED_PARAM_STRING, nodeset) < 0)
                 goto cleanup;
+
+            nodeset = NULL;
+
             break;
 
         default:
@@ -7004,6 +7007,7 @@ qemuDomainGetNumaParameters(virDomainPtr dom,
     ret = 0;
 
 cleanup:
+    VIR_FREE(nodeset);
     virCgroupFree(&group);
     if (vm)
         virDomainObjUnlock(vm);