fix 8139 netbios in AP mode

[pabloandresm]

fix for NetBIOS only working if WIFI in STA mode and not AP mode

#8139

[earlephilhower]

@pabloandresm, I don't think any maintainers use the NetBIOS lib. Have you personally tried this change with AP mode?

[d-a-v]

pushing to v4 per still in discussion

edit:
Approving per feedback.
Changes look good, maybe not fully aware of all network states (ap+sta?), also not ethernet aware.
Netbios users will report back in case of further issues.

[mcspr]

pushing to v4 per still in discussion

edit: Approving per feedback. Changes look good, maybe not fully aware of all network states (ap+sta?), also not ethernet aware. Netbios users will report back in case of further issues.

why not upcb->local_ip though? we do write a low level code interacting with the lwip here
why mix in WiFi class at all?

why not the previously suggested ip_current_dest_addr()
or, in case that is broadcast for whatever reason, ip_current_netif() and get local ip from there?

[d-a-v]

@mcspr As no-one can make and test a more robust change, I suggest, as part of the current freezing process, to merge this bugfix before of after adding this comment

// Note from maintainers: for further improvements, see
// see https://github.com/esp8266/Arduino/pull/8140#discussion_r654549861
// and https://github.com/esp8266/Arduino/pull/8140#issuecomment-1159587969
if (WiFi.getMode()==WIFI_STA)
...

[mcspr]

@d-a-v let me check the change and get back to you... it also seems to generate a malformed packet