Update goldfish-3.4 branch to match android-4.4.2_r1

This pull request updates the `b2g-goldfish-3.4` branch to match the source revision (6dff53caa619cef08ef4cfae48d3f186b0568a0f) mentioned in the `android-4.4.2_r1` tag of `prebuilts/qemu-kernel`, which is what we're currently using for `emulator-kk`, which is the only goldfish where we currently use a 3.4 kernel.