drivers: pinctrl: create Tegra DM pinctrl driver

The existing pinctrl driver available for Tegra SOC is well
designed, but it lacks DM support. Let's add a DM compatible
overlay, which allows use of the device tree, along with preserving
backward compatibility with all existing setups and the ability
to use it in SPL board configuration stage.

Signed-off-by: Svyatoslav Ryhel <clamor95@gmail.com>