client: fix -v option to not require argument

Reported-by: Bryan Christianson <bryan@whatroute.net>
Fixes: d622b222a9 ("chronyc: add wider output option")

client.c

@@ -3656,7 +3656,7 @@ main(int argc, char **argv)
   optind = 1;
 
   /* Parse short command-line options */
-  while ((opt = getopt(argc, argv, "+46acdef:h:mnNp:u:v:w")) != -1) {
+  while ((opt = getopt(argc, argv, "+46acdef:h:mnNp:u:vw")) != -1) {
     switch (opt) {
       case '4':
       case '6':