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: 6551a7fe ("rust: error: Add Error::from_errno{_unchecked}()")
Reported-by: Miguel Ojeda <ojeda@kernel.org>
Link: https://github.com/Rust-for-Linux/linux/issues/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>