ip link: make apply_bridge synchronous and fix style

apply_bridge contains no .await calls, so the async annotation is
unnecessary.  Make it a regular fn and drop the .await at the call
site in add.rs.

Also replace the `if let Some(ref addr) = self.field` pattern with the
more idiomatic Rust 2024 `if let Some(addr) = &self.field` style
already used elsewhere in the file.

Signed-off-by: Gris Ge <cnfourt@gmail.com>

Author: cathay4t

src/ip/link/add.rs

@@ -55,9 +55,7 @@ impl LinkAddCommand {
             InfoKind::Bond => {
                 base_conf.apply(base_conf.apply_bond(&handle).await?)?
             }
-            InfoKind::Bridge => {
-                base_conf.apply(base_conf.apply_bridge().await?)?
-            }
+            InfoKind::Bridge => base_conf.apply(base_conf.apply_bridge()?)?,
             t => {
                 return Err(CliError::from(format!(
                     "Unsupported device type: {t}"

src/ip/link/ifaces/bridge.rs

@@ -426,10 +426,10 @@ impl std::fmt::Display for CliLinkInfoDataBridge {
         write!(f, " mcast_router {}", self.mcast_router)?;
         write!(f, " mcast_query_use_ifaddr {}", self.mcast_query_use_ifaddr)?;
         write!(f, " mcast_querier {}", self.mcast_querier)?;
-        if let Some(ref addr) = self.mcast_querier_ipv4_addr {
+        if let Some(addr) = &self.mcast_querier_ipv4_addr {
             write!(f, " mcast_querier_ipv4_addr {}", addr)?;
         }
-        if let Some(ref addr) = self.mcast_querier_ipv6_addr {
+        if let Some(addr) = &self.mcast_querier_ipv6_addr {
             write!(f, " mcast_querier_ipv6_addr {}", addr)?;
         }
         write!(f, " mcast_hash_elasticity {}", self.mcast_hash_elasticity)?;
@@ -732,7 +732,7 @@ fn format_bridge_timer(v: u64) -> String {
 }
 
 impl LinkBaseConf {
-    pub(crate) async fn apply_bridge(
+    pub(crate) fn apply_bridge(
         &self,
     ) -> Result<LinkMessageBuilder<LinkBridge>, CliError> {
         let mut builder = LinkBridge::new(&self.name);