counter: stm32-timer-cnt: Convert to new counter registration

counter: stm32-timer-cnt: Convert to new counter registration

This fixes device lifetime issues where it was possible to free a live
struct device.

Fixes: ad29937e206f ("counter: Add STM32 Timer quadrature encoder")
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Acked-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20211230150300.72196-21-u.kleine-koenig@pengutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>