staging: r8188eu: remove empty function rtl8188e_stop_thread()

Remove empty function rtl8188e_stop_thread() and related code.

Signed-off-by: Michael Straube <straube.linux@gmail.com>
Link: https://lore.kernel.org/r/20210906190223.11396-36-straube.linux@gmail.com


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