rust: fix clippy ptr_arg warnings

rust: fix clippy ptr_arg warnings

error: writing `&Vec` instead of `&[_]` involves a new object where a slice will do
   --> src/dns/log.rs:371:29
    |
371 | pub fn dns_print_addr(addr: &Vec<u8>) -> std::string::String {
    |                             ^^^^^^^^ help: change this to: `&[u8]`
    |
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#ptr_arg