P2P: Use the P2P Device management interface in wpas_p2p_remove_client()

P2P: Use the P2P Device management interface in wpas_p2p_remove_client()

As wpas_p2p_remove_client() is not necessarily called from the interface
used to manage the P2P Device operations, when removing a client, use
the P2P management interface to iterate over the saved networks and
remove the relevant entries form the P2P GO network blocks.

Signed-off-by: Ben Rosenfeld <ben.rosenfeld@intel.com>