soc/tegra: fuse: Add RAM code reader helper

Needed for the EMC and MC drivers to know what timings from the DT to
use.

Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>