Provide common code for using memory-backed region devices.
This allows in-memory buffers to act as a region device.
Change-Id: I266cd07bbfa16a427c2b31c512e7c87b77f47718
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/9131
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>