ocfs2: replace deprecated strcpy in ocfs2_create_xattr_block

ocfs2: replace deprecated strcpy in ocfs2_create_xattr_block

strcpy() has been deprecated [1] because it performs no bounds checking on
the destination buffer, which can lead to buffer overflows.  Replace it
with the safer strscpy(), and copy directly into '->xb_signature' instead
of using the start of the struct as the destination buffer.

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strcpy
Link: https://lkml.kernel.org/r/20251118185345.132411-2-thorsten.blum@linux.dev
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Jun Piao <piaojun@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>