tests: Allow time for go_neg_pbc() GO Neg Resp to go out

tests: Allow time for go_neg_pbc() GO Neg Resp to go out

It was possible for the not-pre-authorized GO Negotiation case to end up
starting new GO Negotiation before the GO Negotiation Response frame
with status=1 was transmitted. While this works for group formation, it
could reduce test coverage for the common case where that response is
received. At a small sleep to make it less likely for this unexpected
sequence to happen during testing.

Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>