xfs: Replace strncpy with memcpy

xfs: Replace strncpy with memcpy

The changes modernizes the code by aligning it with current kernel best
practices. It improves code clarity and consistency, as strncpy is deprecated
as explained in Documentation/process/deprecated.rst. This change does
not alter the functionality or introduce any behavioral changes.

Suggested-by: Dave Chinner <david@fromorbit.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Signed-off-by: Marcelo Moreira <marcelomoreira1905@gmail.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>