huawei: check ^NWTIME not ^NTCT for time support; fix TZ offset
Use ^NWTIME
instead of ^NTCT
to check for support ^NWTIME
. ^NTCT
seems to be used to enable or disable ^NWTIME
messages.
Also don't add the DST offset to the TZ offset (as it is already included there).
These commits make the time interface work for my E3372h stick and display correctly:
$ mmcli -m a --time
----------------------
Time | current: 2023-07-01T21:49:21+02
----------------------
Timezone | current: 120
| dst offset: 60