Revert "add private_lib for NL80211 and wext driver."

This reverts commit 0b2ed660d9dd3043af4c00dfd2ec0811cfdea78f.
Revert "driver_wext: declare wext private lib functions up front else 4.2 build will fail"

This reverts commit 9d6a26ee93ace437eda351c5be1ec11952e802f6.