ubsan: Remove 1-element array usage in debug reporting

The "type_name" character array was still marked as a 1-element array.
While we don't validate strings used in format arguments yet, let's fix
this before it causes trouble some future day.

Link: https://lore.kernel.org/r/20240424162739.work.492-kees@kernel.org


Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>