vsock: Refactor while let loop into for loop to fit clippy demands.

clippy complains about the while let loop, so we change it to for loop
to fit in the demands.

Signed-off-by: Li Zebin <cutelizebin@gmail.com>

Author: cutelizebin

crates/vsock/src/vhu_vsock_thread.rs

@@ -453,11 +453,11 @@ impl VhostUserVsockThread {
 
         let queue = vring_mut.get_queue_mut();
 
-        let mut queue_iter = queue
+        let queue_iter = queue
             .iter(atomic_mem.memory())
             .map_err(|_| Error::IterateQueue)?;
 
-        while let Some(mut avail_desc) = queue_iter.next() {
+        for mut avail_desc in queue_iter {
             used_any = true;
             let mem = atomic_mem.clone().memory();
 
@@ -611,11 +611,11 @@ impl VhostUserVsockThread {
 
         let queue = vring_mut.get_queue_mut();
 
-        let mut queue_iter = queue
+        let queue_iter = queue
             .iter(atomic_mem.memory())
             .map_err(|_| Error::IterateQueue)?;
 
-        while let Some(mut avail_desc) = queue_iter.next() {
+        for mut avail_desc in queue_iter {
             used_any = true;
             let mem = atomic_mem.clone().memory();