find7: Actually update our MAC address

Fix the d'herp we broke with https://github.com/omnirom/android_device_oppo_msm8974-common/commit/3cb92214e11f48b8a7a20fb227d0ec98c0c72f17

Change-Id: I8303bb6f6c4f70a30a2ae72c10d873c62edcb681