PCI: brcmstb: Disable/enable regulators in suspend/resume

If we found power regulators for a device below the Root Port, disable them
during suspend and re-enable them during resume.

If any downstream device can be a wakeup device, do not turn off the
regulators as the device will need them on.

[bhelgaas: drop unused regulator_oops, skip wrapping of .add_bus()/
.remove_bus(), move brcm_pcie_start_link() to .add_bus() in previous patch,
squash WOL checking into this patch]
Link: https://lore.kernel.org/r/20220725151258.42574-6-jim2101024@gmail.com
Link: https://lore.kernel.org/r/20220725151258.42574-7-jim2101024@gmail.com


Signed-off-by: Jim Quinlan <jim2101024@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Tested-by: Florian Fainelli <f.fainelli@gmail.com>