There currently aren't bindings for the Tegra PCIe controller. Work on
this is in progress, but not yet complete. Manually initialize PCIe when
booting from device tree, in order to bring DT support to the same
feature level as board files, which will in turn allow board files to be
deprecated.

PCIe on Harmony requires various regulators to be registered and enabled
before initializing the PCIe controller. Note that since the I2C
controllers are instantiated from DT, we must use i2c_new_device() to
register the PMU rather than i2c_register_board_info().
Signed-off-by: Stephen Warren <swarren@nvidia.com>