numa: Fixed the memory leak of numa error message

object_get_canonical_path_component() returns a string which
must be freed using g_free().

Signed-off-by: Zhang Yi <yi.z.zhang@linux.intel.com>
Reviewed-by: Pankaj gupta <pagupta@redhat.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Message-Id: <51ba6d7d0333a5517d824a870dd20887156dd15a.1546399191.git.yi.z.zhang@linux.intel.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>

numa.c

@@ -533,6 +533,7 @@ void memory_region_allocate_system_memory(MemoryRegion *mr, Object *owner,
             error_report("memory backend %s is used multiple times. Each "
                          "-numa option must use a different memdev value.",
                          path);
+            g_free(path);
             exit(1);
         }