misc: net_util: streamline error Display::fmt()

The changes were mostly automatically applied using the Python
script mentioned in the first commit of this series.

Signed-off-by: Philipp Schuster <philipp.schuster@cyberus-technology.de>
On-behalf-of: SAP philipp.schuster@sap.com

net_util/src/lib.rs

@@ -40,7 +40,7 @@ pub use tap::{Error as TapError, Tap};
 
 #[derive(Error, Debug)]
 pub enum Error {
-    #[error("Failed to create a socket: {0}")]
+    #[error("Failed to create a socket")]
     CreateSocket(#[source] IoError),
 }