Enable APFv6 mDNS offload for records without priority

This commit enables APFv6-based mDNS offload for records that lack a
properly configured priority value. While third-party apps cannot
configure priority in the overlay, their mDNS offload use case should
still be supported.

Test: TH
Change-Id: I7c1b291986730c999f5f4415d6dce162ea6bf497
2 files changed