refclock: check all driver options

In each driver provide a list of supported options and abort when an
unknown option is specified in the refclock directive.

refclock_pps.c

@@ -48,12 +48,15 @@ struct pps_instance {
 };
 
 static int pps_initialise(RCL_Instance instance) {
+  const char *options[] = {"clear", NULL};
   pps_handle_t handle;
   pps_params_t params;
   struct pps_instance *pps;
   int fd, edge_clear, mode;
   char *path;
 
+  RCL_CheckDriverOptions(instance, options);
+
   path = RCL_GetDriverParameter(instance);
   edge_clear = RCL_GetDriverOption(instance, "clear") ? 1 : 0;