Interworking: Prefer last added network during network selection

Interworking: Prefer last added network during network selection

Previously, any network block could be used to select the BSS to connect
to when processing scan results after Interworking network selection.
This can result in somewhat unexpected network selection in cases where
credential preferences indicated that a specific network was selected,
but another network ended up getting used for the connection. While the
older networks continue to be valid, add special processing for this
initial post-interworking-connect case to get more consistent network
selection to match with the Interworking network selection result.

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