t6-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: I9dc54cdbaed2b8d11153e61d4e97bf5bac9f3a11
(cherry picked from commit c9fae7c6be5a3e72f781d5486244ddf580716af0)