Some dsmesock disconnect issues were found from mce code tree. As the
usb-moded code is derived from mce, similar fixes need to be made also
here.

Avoid recursive process watchdog quits during disconnect by doing the
quitting only once / connect after removal of socket io watch.

Drop reconnect attempts on I/O error situations as they are unlikely
to do any good and can lead to further recursive behavior.

Do not initiate new dsmesock connections while device is shutting down.
Signed-off-by: Simo Piiroinen <simo.piiroinen@jollamobile.com>