wifi: remove p2p interface on supplicant stop

remove p2p interface on wpa_supplicant stop
so next time it is started it won't fail when trying
to create p2p again

Change-Id: I7a4c5e9a82a013afc75548d175d5850d67fcd927
wifi: support adding p2p0 when starting wpa_supplicant

For TI wlan chips in p2p mode we need this omapzoom cherry-pick
to start p2p0 correctly.

http://www.omapzoom.org/?p=platform/hardware/libhardware_legacy.git;a=commit;h=ccb4c24db795059f1df365d313d80c6b269bc55e
By: Arik Nemtsov <arik@wizery.com>
On: Tue, 31 Jul 2012 21:21:20

Original commit description:
Add p2p0 using an NL80211 command when wpa_supplicant is started, and
p2p_supported is enabled.

Change-Id: Ibc0ad138513f024672642cc5764a81510aa38625
Signed-off-by: Hashcode <hashcode0f@gmail.com>

Conflicts:
	wifi/wifi.c