P2P: Fix group interface addition failure properly for concurrent case

P2P: Fix group interface addition failure properly for concurrent case

It was possible for a P2P group formation failure to result in a
concurrent station mode operation getting disconnected in the specific
error case where group interface addition fails after a successful GO
Negotiation. Fix this by skipping the wpas_p2p_group_delete() call in
this specific case since the group interface does not exists anymore at
the point wpas_group_formation_completed() gets called.

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