FT: Check hapd->wpa_auth before RRB internal delivery

FT: Check hapd->wpa_auth before RRB internal delivery

A malicious station could try to do FT-over-DS with a non WPA-enabled
BSS. When this BSS is located in the same hostapd instance, internal RRB
delivery will be used and thus the FT Action Frame will be processed by
a non-WPA enabled BSS. This processing used to crash hostapd as
hapd->wpa_auth is NULL. If the target BSS is on a different hostapd
instance, it will not listen for these packets and thus not crash.

Fix this by checking hapd->wpa_auth before delivery.

Signed-off-by: Michael Braun <michael-dev@fami-braun.de>