travelmate: treat an unresolvable captive portal as an error

travelmate: treat an unresolvable captive portal as an error

'trm_netcheck' only ever fired on "net nok", but f_net() reports a detected
portal as "net cp" regardless of 'trm_captive' - the option gates the portal
handling, not the detection. With 'trm_captive' disabled travelmate neither
adds the portal domain to the dhcp rebind allowlist nor runs a login script,
so that state can never resolve on its own: the uplink stayed connected as
"net cp '<domain>'" forever, the vpn was never brought up (it requires "net
ok") and 'trm_netcheck' never kicked in - travelmate stuck to exactly the
uplink the option is meant to get rid of.

Downgrade "net cp" to "net nok" in f_net() when the portal handling is off.
With 'trm_captive' enabled nothing changes.

Signed-off-by: Dirk Brenken <redacted>