clocksource/drivers/stm32-lp: Add module owner

The conversion to modules requires a correct handling of the module
refcount in order to prevent to unload it if it is in use. That is
especially true with the clockevents where there is no function to
unregister them.

The core time framework correctly handles the module refcount with the
different clocksource and clockevents if the module owner is set.

Add the module owner to make sure the core framework will prevent
stupid things happening when the driver will be converted into a
module.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Reviewed-by: Will McVicker <willmcvicker@google.com>
Link: https://lore.kernel.org/r/20250602151853.1942521-3-daniel.lezcano@linaro.org