serial: m32r_sio: Drop redundant .data assignment

With the timer converted to using the new timer_setup()/from_timer() API,
setting the .data field is redundant (and the field will be removed soon),
so drop it.

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: linux-serial@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>