Avoid leak in qemuParseRBDString on failure of qemuAddRBDHost

If qemuAddRBDHost fails due to parsing problems or OOM, then
qemuParseRBDString cleanup is skipped causing a memory leak.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

src/qemu/qemu_command.c

@@ -3404,9 +3404,9 @@ static int qemuParseRBDString(virDomainDiskDefPtr disk)
                         break;
                     }
                 }
-                if (qemuAddRBDHost(disk, h) < 0) {
-                    return -1;
-                }
+                if (qemuAddRBDHost(disk, h) < 0)
+                    goto error;
+
                 h = sep;
             }
         }