SME: Fix IBSS setup after shared key/FT/FILS association

SME: Fix IBSS setup after shared key/FT/FILS association

wpa_s->sme.auth_alg could have been left to a previously value other
than WPA_AUTH_ALG_OPEN if IBSS network is used after an association that
used shared key, FT, or FILS authentication algorithm. This could result
in the IBSS setup failing due to incorrect authentication processing
steps.

Fix this by setting wpa_s->sme.auth_alg = WPA_AUTH_ALG_OPEN whenever
starting an IBSS (or mesh, for that matter) network.

Signed-off-by: Jouni Malinen <j@w1.fi>