Merge "Disable accept_ra upon IPv6 default route has gone for dual-stack devices." am: 1869751164 am: 97187181c3

Original change: https://android-review.googlesource.com/c/platform/packages/modules/NetworkStack/+/1704765

Change-Id: I4cbb82aa9e54cf1b92d78b21aab267c22eb317be