rust: remove unnecessary nested match

Bug: #4605

rust/src/dhcp/logger.rs

@@ -59,16 +59,8 @@ impl DHCPLogger {
 
     pub fn do_log(&self, tx: &DHCPTransaction) -> bool {
         if !self.extended {
-            match self.get_type(tx) {
-                Some(t) => {
-                    match t {
-                        DHCP_TYPE_ACK => {
-                            return true;
-                        }
-                        _ => {}
-                    }
-                }
-                _ => {}
+            if let Some(DHCP_TYPE_ACK) = self.get_type(tx){
+                return true;
             }
             return false;
         }

rust/src/lib.rs

@@ -63,7 +63,6 @@
 #![allow(clippy::while_let_loop)]
 #![allow(clippy::redundant_pattern_matching)]
 #![allow(clippy::field_reassign_with_default)]
-#![allow(clippy::collapsible_match)]
 
 #[macro_use]
 extern crate nom;