rust: error: add missing newline to pr_warn! calls

Added missing newline at the end of pr_warn! usage
so the log is not missed.

Fixes: 6551a7f ("rust: error: Add Error::from_errno{_unchecked}()")
Reported-by: Miguel Ojeda <ojeda@kernel.org>
Link: Rust-for-Linux#1139
Signed-off-by: Alban Kurti <kurti@invicto.ai>
Link: https://lore.kernel.org/r/20250206-printing_fix-v3-2-a85273b501ae@invicto.ai
[ Replaced Closes with Link since it fixes part of the issue. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

Author: albankurti

rust/kernel/error.rs

@@ -107,7 +107,7 @@ impl Error {
         } else {
             // TODO: Make it a `WARN_ONCE` once available.
             crate::pr_warn!(
-                "attempted to create `Error` with out of range `errno`: {}",
+                "attempted to create `Error` with out of range `errno`: {}\n",
                 errno
             );
             code::EINVAL