If the checksum coverage field in the UDPLITE header is the length
of the complete UDPLITE packet, the packet has full checksum coverage.
SO fix the condition.

Reviewed by: kevlo
MFC after: 3 days


git-svn-id: svn+ssh://svn.freebsd.org/base/head@272323 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f