P2P: Fix P2P_CONNECT-auto fallback to GO Neg with group interface

P2P: Fix P2P_CONNECT-auto fallback to GO Neg with group interface

If a separate P2P group interface was used, P2P_CONNECT-auto fallback to
GO Negotiation could result in use of freed memory and segmentation
fault. This happened in cases where the peer GO was found in some old
scans, but not in the first scan triggered by the P2P_CONNECT-auto
command ("P2P: Peer was found running GO in older scan -> try to join
the group" shows up in the debug log). In addition, the GO would still
need to reply to PD Request to allow this code path to be triggered.

When five scans for the GO were completed in this sequence, the P2P
group interface was removed as part of falling back to GO Negotiation.
However, that ended up dereferencing the freed wpa_s instance at the end
of scan event processing. Fix this by reordering code a bit and breaking
out from EVENT_SCAN_RESULTS processing if the interface could have been
removed.

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