Add support for Norrin board

Norrin (PM370) is an NVIDIA Tegra124 Chromebook reference platform.
It is also called "nyan" in the ChromeOS tree. Note that "nyan rev0"
actually referred to Venice2 not Norrin. However, most references to
"nyan rev0" are gone now.

Signed-off-by: Allen Martin <amartin@nvidia.com>
Signed-off-by: Stephen Warren <swarren@nvidia.com>