wpa_supplicant: Don't enable NL80211 unconditionally

This should be enabled by BOARD_WPA_SUPPLICANT_DRIVER, not as a
hard default

(was) Change-Id: I18d08fde3dd6180267bb60677bbc75fc3b7726ef

Change-Id: I46599e32cbed16ff61a73068d5c68aa8b2ddf742