openamp: add core address translation support

There are SoCs that have different memory maps for device and driver.
Therefore the shared memory between them has different values and we
need to convert the addresses.

This commit introduces address translation support for OpenAMP:
- implements the address translation functions;
- returns the I/O operations used for address translation.
The ops can be used in Libmetal (see metal_io_init()).

Signed-off-by: Iuliana Prodan <iuliana.prodan@nxp.com>