USB: serial: digi_acceleport: clean up set_termios

Clean up set_termios() by adding missing white space around operators
and making a couple of continuation lines more readable.

Also drop a couple of redundant braces.

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>