Allow wpa_supplicant to write to files in /proc/net.

This is needed for interface configuration - see e.g. nl80211_configure_data_frame_filters.

Bug: 77903086
Test: Device boots, denial not seen, wifi works

(cherry picked from commit 72ed6152)

Change-Id: Ia781e7c56f6e8e77e654cd28ca34de09180e2213
Merged-In: Ia55c4af1fcee75ada0e67a162fdb92ecc0089312