Postpone updating of wpa_s->current_bss till association event

Postpone updating of wpa_s->current_bss till association event

In the case of driver-based BSS selection, a bssid_hint in the connect
request might not result in to the selection of the same BSS. Thus,
postpone the updation of the wpa_s->current_bss till the association
event is received unless the BSSID is forced. This fixes issues where
wpa_s->current_bss may end up being updated to point to the BSS that
wpa_supplicant provided as a hint for a roaming case, but then not
restored if the driver decides to "return" to the current BSS instead.
This could result in some operations (e.g., WNM BSS TM response) not
working properly due to incorrect BSS being identified in
wpa_s->current_bss.

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