pwm: renesas-tpu: Drop confusing registered message

During device probe, the message

    TPU PWM -1 registered

is printed.

While the "-1" looks suspicious, it is perfectly normal for a device
instantiated from DT.

Remove the message, as there are no non-DT users left, and other drivers
don't print such messages either.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>