m32r_sio: remove dependency on struct serial_uart_config

The struct serial_uart_config is hardly used at all, and the
use case like this one are somewhat needless.  Remove the
trivial usage so that we can remove serial_uart_config.

Since the type field isn't really used at all, we also delete
the initialization and references of it here as well.

Cc: Hirokazu Takata <takata@linux-m32r.org>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Acked-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>