ocfs2: move ocfs2_xattr_handlers and ocfs2_xattr_handler_map to .rodata

ocfs2: move ocfs2_xattr_handlers and ocfs2_xattr_handler_map to .rodata

This makes it harder for accidental or malicious changes to
ocfs2_xattr_handlers or ocfs2_xattr_handler_map at runtime.

Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: ocfs2-devel@lists.linux.dev
Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>
Link: https://lore.kernel.org/r/20230930050033.41174-21-wedsonaf@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>