P2P: Add group ifname to P2P-PROV-DISC-* events

P2P: Add group ifname to P2P-PROV-DISC-* events

If Provision Discovery Request is sent for GO role (i.e., P2P Group ID
attribute is included), add the group interface name to the control
interface event on the GO. This makes it easier to figure out which
ctrl_iface needs to be used for wps_pbc/wps_pin command to authorize
the joining P2P client.

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