SME: Clear portValid on starting authentication to fix FILS

SME: Clear portValid on starting authentication to fix FILS

The ft_completed for FILS authentication case in
wpa_supplicant_event_assoc() depends on something having cleared
portValid so that setting it TRUE ends up authorizing the port. This
clearing part did not happen when using FILS authentication during a
reassociation within an ESS. Fix this by clearing portValid in
sme_send_authentication() just before the keys are cleared (i.e., the
old connection would not be usable anyway).

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