net_util: trim qualified paths

Import the std modules used across the crate instead of spelling the
full paths at every use site.

Signed-off-by: Henry Hrvoje Tonkovac <htonkovac@gmail.com>
Assisted-by: Claude:Opus-4.8

net_util/src/mac.rs

@@ -131,7 +131,7 @@ pub enum MacAddrParseError {
 impl FromStr for MacAddr {
     type Err = MacAddrParseError;
 
-    fn from_str(s: &str) -> std::result::Result<Self, Self::Err> {
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
         MacAddr::parse_str(s).map_err(|_| MacAddrParseError::InvalidValue(s.to_owned()))
     }
 }