staging: rtl8723bs: Remove function pointer cancel_thread

Remove function pointer cancel_thread and use rtl8723b_stop_thread
directly to increase readability.

Signed-off-by: Philipp Hortmann <philipp.g.hortmann@gmail.com>
Link: https://lore.kernel.org/r/e4fdff174a8ddc6cd62232e0aac8e23f4f34b1b9.1730749680.git.philipp.g.hortmann@gmail.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>