modemmanager: do not disable modem on reconnect

modemmanager: do not disable modem on reconnect

If the modem loses the connection, an attempt is made to re-establish the
connection via the report-down script.

Until now, the modem was disabled when the modem processed the teardown of
the modemmanager protohandler. The immediate up events of netifd renables
the modem right away. This takes time, which is not necessary.

This commit changes the behavior so that the modem is not disabled when
the modemmanager is disconnected via the report-down script.

Signed-off-by: Florian Eckert <redacted>