Revert "shell/commands: fix, only accept proper pong response"

[benpicco]

Contribution description

This reverts commit 5e1558b as it breaks brodcast ping.

Testing procedure

Run ping6 ff02::1 with at least one other node in the same PAN.

Expected results

2019-09-10 19:20:39,932 - INFO #  ping6 ff02::1%7
2019-09-10 19:20:39,955 - INFO # 12 bytes from fe80::8d1b:3202:ae20:bb66: icmp_seq=0 ttl=64 rssi=-34 dBm time=7.861 ms
2019-09-10 19:20:39,960 - INFO # 12 bytes from fe80::3030:81da:f70c:5e06: icmp_seq=0 ttl=64 rssi=-66 dBm time=16.176 ms (DUP!)
2019-09-10 19:20:40,947 - INFO # 12 bytes from fe80::8d1b:3202:ae20:bb66: icmp_seq=1 ttl=64 rssi=-37 dBm time=6.931 ms
2019-09-10 19:20:41,949 - INFO # 12 bytes from fe80::3030:81da:f70c:5e06: icmp_seq=2 ttl=64 rssi=-70 dBm time=7.988 ms
2019-09-10 19:20:41,952 - INFO # 
2019-09-10 19:20:41,956 - INFO # --- ff02::1 PING statistics ---
2019-09-10 19:20:41,961 - INFO # 3 packets transmitted, 3 packets received, 1 duplicates, 0% packet loss

Actual results

2019-09-10 19:21:48,467 - INFO #  ping6 ff02::1%7
2019-09-10 19:21:51,469 - INFO # 
2019-09-10 19:21:51,473 - INFO # --- ff02::1 PING statistics ---
2019-09-10 19:21:51,478 - INFO # 3 packets transmitted, 0 packets received, 100% packet loss

Issues/PRs references

this reverts #12159 but the real culprit was #11933 😉

[miri64]

Rather then reverting to an already broken state, we should fix it properly. A check for ipv6_addr_is_multicast(&data->host) should be enough.

[miri64]

See #12197 as an alternative.