Add support for Norrin

Add support for Tegra124 Norrin FFD reference board (PM370).  Pinmux
is based on PM370_T124_customer_pinmux_1.1 spreadsheet.

Signed-off-by: Allen Martin <amartin@nvidia.com>
[swarren, kept supported_boards[] sorted]
Signed-off-by: Stephen Warren <swarren@nvidia.com>