USB: serial: metro-usb: fix up coding style errors

This fixes up all of the coding style errors, and removes the initial,
unneeded comments on how to load the module and the old changelog which
are no longer needed.

There are still a number of coding style warnings left, I'll get to them
later.

Cc: Aleksey Babahin <tamerlan311@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>