P2P: Add deinit_p2p_cli op to clear P2P client driver state

P2P: Add deinit_p2p_cli op to clear P2P client driver state

On P2P group removal, the GO is deinitialized correctly (and the vif
mode is set back to sta in case of nl80211), but the P2P client mode
wasn't deinitialized, and the nl80211 vif stays in P2P client mode.

Add a new deinit_p2p_cli op (similar to deinit_ap), which currently only
sets the interface back to station mode.

Signed-hostap: Eliad Peller <eliad@wizery.com>
intended-for: hostap-1