staging: r8188eu: make two functions static

The functions rtw_join_timeout_handler() and
_rtw_scan_timeout_handler() are only used in os_dep/mlme_linux.c.
Make them static.

Tested-by: Philipp Hortmann <philipp.g.hortmann@gmail.com> # Edimax N150
Signed-off-by: Michael Straube <straube.linux@gmail.com>
Link: https://lore.kernel.org/r/20220831053639.8559-2-straube.linux@gmail.com


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