It was possible for the 5 GHz PKEX channels to be enabled, e.g., when
running "ap_ht40_csa2 dpp_pkex_no_responder" test sequence, and that
resulted in a failure in dpp_pkex_no_responder due to the unexpectedly
long wait needed for the DPP-FAIL event. Increase the wait time to allow
for 5 GHz PKEX channels to be probed.
Signed-off-by: Jouni Malinen <j@w1.fi>