Set current_ssid before changing state to ASSOCIATING

Set current_ssid before changing state to ASSOCIATING

For hidden GBK encoding of a Chinese SSID, both the UTF-8 and GBK
encoding profiles are added into wpa_supplicant to make sure the
connection succeeds. In this situation, wpa_supplicant_select_network()
will not be called so current_ssid is NULL when association begins.

Android monitors the WPA_EVENT_STATE_CHANGE event to get the SSID and
BSSID. When connecting to a Chinese SSID, in case of association
rejection happens, Android will report null SSID to OEM APP because
current_ssid is updated after wpa_supplicant_set_state(wpa_s,
WPA_ASSOCIATING), which may cause confusion.

Fix this by setting the current_ssid before changing state to
ASSOCIATING.

Signed-off-by: Jouni Malinen <quic_jouni@quicinc.com>