ARM: tegra: Add IRAM node on Tegra30

IRAM is a static RAM that consists of four contiguous 64 KiB blocks,
it is currently used to store CPU resume code, utilized by the video
decoder engine and could be used as a general-purpose fast memory.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>