nfc-poll: disconnect from device if error in order to prevent from keep up RF field which have side effects: its power-consumming, device can became warm and it generates useless radiofrequencies.

examples/nfc-poll.c

@@ -137,10 +137,10 @@ main (int argc, const char *argv[])
         };
       }
     } else {
+      nfc_disconnect (pnd);
       nfc_perror (pnd, "nfc_initiator_poll_targets");
       exit (EXIT_FAILURE);
     }
-
     nfc_disconnect (pnd);
   }