Avoid incorrect nlmsg_type in returned INetDiagMessage

The target parsing mechanism focuses on SOCK_DIAG_BY_FAMILY.
The returned message with unexpected messages will cause
the parsing mechanism does not work as intended. Thus,
skip parsing on incorrect message.

Bug: 145275899
Bug: 142035706
Test: atest NetworkStackTests NetworkStackNextTests
Change-Id: I73ab979c735268551a54b0a88de18c6d1a2068c4