bump version to 5.15 am: 8be3a91a72 am: a6d2500b20 am: acd4b27208

Original change: https://android-review.googlesource.com/c/platform/external/ethtool/+/2804539

Change-Id: I3a366d3b4e42609b0b5bda3188035bef374b1a9d
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>