ANDROID: fix build for missing ETH_ALEN definition am: 7608e136bd am: 3799b1e13f am: f751c1415e

Original change: https://android-review.googlesource.com/c/platform/external/iptables/+/1650937

Change-Id: I2d1d6c9df66bb0908ecd75f3ddba7712819ff6a8