SshConn: wrong call in main() corrected

In the Function main() the SshConn is called with a wrong number of argumentes. One of the argumentes is a logger. This logger is not expected anymore and is removed.

Signed-off-by: Johannes Kroop <johkroop@gmail.com>
serial_conn.py: Workaround for serial connection

In the function __wait_for_known_boot_state the serial connection is restarted
to avoid sticking in th loop.

Signed-off-by: Johannes Kroop <johkroop@gmail.com>
serial_conn.py: small mistake corrected

Signed-off-by: Johannes Kroop <johkroop@gmail.com>