USB: serial: ir_usb: Clean up the worst of it, remove exciting 'crash on open' feature

- Drivers don't call ldisc termios methods. They certainly don't call
them the way this one does - remove wrong call
- The tty buffer code isn't designed to be abused from IRQ handlers and
the new buffering removes the need for the uglies involved - fix them
- Style
- Remove incorrect baud and change handling for termios changes

The driver now has some style, but not a lot - it goes insane if you have
two dongles for example as it continues to use global variables for per
dongle state. That bit isn't my problem.

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>