USB: serial: ftdi_sio: remove startup message

No one needs to know that the driver is loaded (almost all other USB
serial drivers are now quiet), so just load quietly.

Also remove unused, and unneeded version information from the driver,
that was pointless.

Cc: Uwe Bonnes <bon@elektron.ikp.physik.tu-darmstadt.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>