fixes subtle bug introduced in commit #c35b1882

hinted by gcc:

../../module/zfs/zio_inject.c: In function ‘zio_handle_io_delay’:
../../module/zfs/zio_inject.c:382:3: warning: this ‘if’ clause does not guard... [-Wmisleading-indentation]
   if (handler->zi_record.zi_freq != 0 &&
      ^~
      ../../module/zfs/zio_inject.c:384:4: note: ...this statement, but the latter is misleadingly indented as if it is guarded by the ‘if’
          continue;
	      ^~~~~~~~

module/zfs/zio_inject.c

@@ -380,8 +380,9 @@ zio_handle_io_delay(zio_t *zio)
 			continue;
 
 		if (handler->zi_record.zi_freq != 0 &&
-		    spa_get_random(100) >= handler->zi_record.zi_freq);
+		    spa_get_random(100) >= handler->zi_record.zi_freq) {
 			continue;
+		}
 
 		if (vd->vdev_guid == handler->zi_record.zi_guid) {
 			seconds = handler->zi_record.zi_timer;