refactor(udp): remove unnecessary return

No need to `return Ok(())` early, given the final `return Ok(())` at the end of
the function. Makes it consistent with other `send` implementations. Makes it
consistent with early returns being errors only.

quinn-udp/src/unix.rs

@@ -341,8 +341,6 @@ fn send(
                     if e.raw_os_error() != Some(libc::EMSGSIZE) {
                         return Err(e);
                     }
-
-                    return Ok(());
                 }
             }
         }