nfc-read-forum-tag3: remove redundant error

switch case was redundant as getopt was already telling the issue:

  nfc-read-forum-tag3: option requires an argument -- 'o'
  Option -o requires an argument.

This fixes also a problem reported by Coverity about missing break:

CID 1090330 (nfc-tools#1 of 1): Missing break in switch (MISSING_BREAK)
  unterminated_case: This case (value 63) is not terminated by a 'break' statement.

utils/nfc-read-forum-tag3.c

@@ -178,9 +178,6 @@ main(int argc, char *argv[])
       case 'o':
         ndef_output = optarg;
         break;
-      case '?':
-        if (optopt == 'o')
-          fprintf(stderr, "Option -%c requires an argument.\n", optopt);
       default:
         print_usage(argv[0]);
         exit(EXIT_FAILURE);