s4-common: Fix wpa_supplicant overlays

The p2p_supplicant service sets up both the p2p and non-p2p interfaces.
We need to associate both overlays in this service (the wpa_supplicant
service actually never runs).

Change-Id: I6dabf1b76c1002493df4e9294f89333b1ec94008
Merge pull request #5 from CyanogenMod/cm-11.0

s4-common: Fix wpa_supplicant overlays