mtd: rawnand: tegra: Add runtime PM and OPP support

The NAND on Tegra belongs to the core power domain and we're going to
enable GENPD support for the core domain. Now NAND must be resumed using
runtime PM API in order to initialize the NAND power state. Add runtime PM
and OPP support to the NAND driver.

Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>