[ARM] Orion: support D0 5281 silicon

On D0 5281 SoCs, we need to disable the wait-for-interrupt
instruction due to an erratum.

Signed-off-by: Lennert Buytenhek <buytenh@marvell.com>
Signed-off-by: Nicolas Pitre <nico@marvell.com>
Acked-by: Martin Michlmayr <tbm@cyrius.com>