staging: rtl8723bs: convert function to static

function chk_sta_is_alive() is used only inside core/rtw_ap.c
so remove the prototype and convert it to static.

Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Fabio Aiuto <fabioaiuto83@gmail.com>
Link: https://lore.kernel.org/r/20210623130103.7727-1-fabioaiuto83@gmail.com


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