wps_supplicant.h assumes that 'struct wpa_bss' is forward declared if
CONFIG_WPS is not defined. With the later inclusion of
600-ubus_support, the issue manifests in warnings like these:
wps_supplicant.h:113:15: warning: 'struct wpa_bss' declared inside parameter list will not be visible outside of this definition or declaration
struct wpa_bss *bss)
^~~~~~~
This patch forward declares 'struct wpa_bss' regardless.
Signed-off-by: Leon M. George <leon@georgemail.eu>
[commit message facelift]
Signed-off-by: Petr Štetiar <ynezz@true.cz>