register: Add Memory API glue

register: Add Memory API glue

Add memory io handlers that glue the register API to the memory API.
Just translation functions at this stage. Although it does allow for
devices to be created without all-in-one mmio r/w handlers.

This patch also adds the RegisterInfoArray struct, which allows all of
the individual RegisterInfo structs to be grouped into a single memory
region.

Signed-off-by: Peter Crosthwaite <[email protected]>
Signed-off-by: Alistair Francis <[email protected]>
Message-id: f7704d8ac6ac0f469ed35401f8151a38bd01468b.1467053537[email protected]
Reviewed-by: Peter Maydell <[email protected]>
Signed-off-by: Peter Maydell <[email protected]>