USB: serial: simple: add libtransistor console

USB: serial: simple: add libtransistor console

BugLink: http://bugs.launchpad.net/bugs/1778265
commit fe710508b6ba9d28730f3021fed70e7043433b2e upstream.

Add simple driver for libtransistor USB console.
This device is implemented in software:
https://github.com/reswitched/libtransistor/blob/development/lib/usb_serial.c

Signed-off-by: Collin May <collin@collinswebsite.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>