staging: r8188eu: make update_TSF() and correct_TSF() static

The functions update_TSF() and correct_TSF() are only used in
rtw_mlme_ext.c. Make them static.

Signed-off-by: Michael Straube <straube.linux@gmail.com>
Link: https://lore.kernel.org/r/20220715062908.8547-5-straube.linux@gmail.com


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