rust: sync: add missing newline in locked_by log example

The pr_info! example in rust/kernel/sync/locked_by.rs was missing
a newline. This patch appends the missing newline to ensure
that log messages for locked resources display correctly.

Fixes: 7b1f55e ("rust: sync: introduce `LockedBy`")
Reported-by: Miguel Ojeda <ojeda@kernel.org>
Closes: Rust-for-Linux#1139
Signed-off-by: Alban Kurti <kurti@invicto.ai>

rust/kernel/sync/locked_by.rs

@@ -55,7 +55,7 @@ use core::{cell::UnsafeCell, mem::size_of, ptr};
 /// fn print_bytes_used(dir: &Directory, file: &File) {
 ///     let guard = dir.inner.lock();
 ///     let inner_file = file.inner.access(&guard);
-///     pr_info!("{} {}", guard.bytes_used, inner_file.bytes_used);
+///     pr_info!("{} {}\n", guard.bytes_used, inner_file.bytes_used);
 /// }
 ///
 /// /// Increments `bytes_used` for both the directory and file.