Building with the attached random configuration file,

drivers/staging/rtl8723au/core/rtw_cmd.c: In function ‘c2h_evt_hdl’:
drivers/staging/rtl8723au/core/rtw_cmd.c:1315:4: error: implicit declaration of
function ‘c2h_handler_8723a’ [-Werror=implicit-function-declaration]
    ret = c2h_handler_8723a(adapter, c2h_evt);
    ^
drivers/staging/rtl8723au/core/rtw_cmd.c: In function ‘rtw_evt_work’:
drivers/staging/rtl8723au/core/rtw_cmd.c:1349:2: error: implicit declaration of
function ‘c2h_id_filter_ccx_8723a’ [-Werror=implicit-function-declaration]
  if (c2h_id_filter_ccx_8723a(ework->u.c2h_evt.id) == true) {
  ^
cc1: some warnings being treated as errors