P2P: Remove WPA_DRIVER_FLAGS_P2P_MGMT option

P2P: Remove WPA_DRIVER_FLAGS_P2P_MGMT option

The option of handling upper layer P2P management operations within the
driver/firmware was originally planned to be used with wpa_supplicant,
but this has not really happened and there is no clear sign of this
being needed in the near term either. This functionality has not been
completed and it is certainly not being kept up-to-date or tested. As
such, it is best to remove it for now and if this or something similar
is needed in the future, it can be brought back once a clear need for it
has been demonstrated first.

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