Do not log when NetworkSpecifier is null

To avoid logging requests with empty capabilities and no
NetworkSpecifier. This also renames the validation functions for clarity
as was suggested in a previous review, and changes the Log.w to Log.i if
the specifier is invalid.

Test: TH
Bug: 397130676
Change-Id: I488b466f83f85ea9f3c067c95c4e01846560dea7
1 file changed