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
Merge pull request #8 from CyanogenMod/cm-11.0

wifi: remove p2p interface on supplicant stop