Fix Clippy warnings for rustc version 1.65

Two warnings have been introduced and both are from
category: needless_borrow
This commit is to remove the needless borrow

Signed-off-by: Mohamed Omar Asaker <mohamed.omarasaker@arm.com>

Author: mohamedasaker-arm

src/back/backend_handler.rs

@@ -97,8 +97,7 @@ impl BackEndHandler {
         }
 
         if opcode.is_admin() {
-            let app =
-                unwrap_or_else_return!((&app).as_ref().ok_or(ResponseStatus::NotAuthenticated));
+            let app = unwrap_or_else_return!(app.as_ref().ok_or(ResponseStatus::NotAuthenticated));
 
             if !app.is_admin() {
                 warn!(

src/key_info_managers/on_disk_manager/mod.rs

@@ -395,7 +395,7 @@ impl OnDiskKeyInfoManager {
             for provider_dir_path in list_dirs(app_name_dir_path)?.iter() {
                 for key_name_file_path in list_files(provider_dir_path)?.iter() {
                     let mut key_info = Vec::new();
-                    let mut key_info_file = File::open(&key_name_file_path).with_context(|| {
+                    let mut key_info_file = File::open(key_name_file_path).with_context(|| {
                         format!(
                             "Failed to open Key Info Mappings file at {:?}",
                             key_name_file_path

src/providers/cryptoauthlib/mod.rs

@@ -191,7 +191,7 @@ impl Provider {
             }
         }
 
-        if None == cryptoauthlib_provider.set_opcodes() {
+        if cryptoauthlib_provider.set_opcodes().is_none() {
             warn!("Failed to setup opcodes for cryptoauthlib_provider");
         }