cli: Workaround possible bug in paramiko

I've seen issues where put() fails with "OSError: Socket is closed"
after a previous timeout while running a command. I haven't been able to
reliably reproduce, but I suspect this could be due to a bug in fabric
(or paramiko). Attempt to work around this by explicitly disconnecting
and reconnecting to the SUT upon timeout (or any other exception).

Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>