chardev: Simplify usage of try_module_get()

try_module_get(NULL) is true, so there is no need to check owner being
NULL.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20231013132441.1406200-2-u.kleine-koenig@pengutronix.de


Signed-off-by: Christian Brauner <brauner@kernel.org>