Tegra186 powergate driver is implemented as power domain driver, power
partition ungate/gate are registered as power_on/power_off callback
functions. There are no direct functions to power gate/ungate host
controller in Tegra186. Host controller driver should add "power-domains"
property in device tree and implement runtime suspend and resume
callback functons. Power gate and ungate is taken care by power domain
driver when host controller driver calls pm_runtime_put_sync and
pm_runtime_get_sync respectively.
Register suspend_noirq & resume_noirq callback functions to allow PCIe to
come up after resume from RAM. Both runtime and noirq pm ops share same
callback functions.