rust: pin-init: examples: fix useless_borrows_in_formatting clippy warning

Clippy 1.97 introduces new `useless_borrows_in_formatting` warning which
fires on the examples as we have `&*expr` where the format macro takes
reference already. Remove the extra borrow.

Link: https://patch.msgid.link/20260505115138.2466966-1-gary@kernel.org
Signed-off-by: Gary Guo <gary@garyguo.net>

rust/pin-init/examples/mutex.rs

@@ -218,7 +218,7 @@ fn main() {
         for h in handles {
             h.join().expect("thread panicked");
         }
-        println!("{:?}", &*mtx.lock());
+        println!("{:?}", *mtx.lock());
         assert_eq!(*mtx.lock(), workload * thread_count * 2);
     }
 }

rust/pin-init/examples/pthread_mutex.rs

@@ -177,7 +177,7 @@ fn main() {
         for h in handles {
             h.join().expect("thread panicked");
         }
-        println!("{:?}", &*mtx.lock());
+        println!("{:?}", *mtx.lock());
         assert_eq!(*mtx.lock(), workload * thread_count * 2);
     }
 }

rust/pin-init/examples/static_init.rs

@@ -117,7 +117,7 @@ fn main() {
         for h in handles {
             h.join().expect("thread panicked");
         }
-        println!("{:?}, {:?}", &*mtx.lock(), &*COUNT.lock());
+        println!("{:?}, {:?}", *mtx.lock(), *COUNT.lock());
         assert_eq!(*mtx.lock(), workload * thread_count * 2);
     }
 }