net: move sockfs_xattr_handlers to .rodata

net: move sockfs_xattr_handlers to .rodata

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

Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: netdev@vger.kernel.org
Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>
Link: https://lore.kernel.org/r/20230930050033.41174-30-wedsonaf@gmail.com
Acked-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>