P2P: Direct global ctrl_iface commands automatically for P2P

P2P: Direct global ctrl_iface commands automatically for P2P

The P2P management operations like P2P_FIND and P2P_CONNECT are not
really specific to any network interface. These are P2P Device level
operations that are in more global device context. Allow those to be
sent through the global control interface without IFNAME parameter.

For now, these commands are directed within wpa_supplicant to the
network interface that initialized the global P2P context. This may
change in the future if a special context is added for P2P operations.
Anyway, such changes can now be done internally within wpa_supplicant
without affecting this global control interface design from external
view point.

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