rust/smb: fix clippy nightly warning

rust/smb: fix clippy nightly warning

error: unnecessary use of `to_vec`
    --> src/smb/smb.rs:1048:62
     |
1048 |         let (name, is_dcerpc) = match self.guid2name_map.get(&guid.to_vec()) {
     |                                                              ^^^^^^^^^^^^^^ help: replace it with: `guid`
     |
     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#unnecessary_to_owned
     = note: `#[deny(clippy::unnecessary_to_owned)]` implied by `#[deny(warnings)]`

And also other uses of to_vec() on already Vec