Revert "PCI: brcmstb: Add control of subdevice voltage regulators"

This reverts commit 93e41f3f.

This is part of a revert of the following commits:

  11ed8b86 ("PCI: brcmstb: Do not turn off WOL regulators on suspend")
  93e41f3f ("PCI: brcmstb: Add control of subdevice voltage regulators")
  67211aad ("PCI: brcmstb: Add mechanism to turn on subdev regulators")
  830aa6f2 ("PCI: brcmstb: Split brcm_pcie_setup() into two funcs")

Cyril reported that 830aa6f2 ("PCI: brcmstb: Split brcm_pcie_setup()
into two funcs"), which appeared in v5.17-rc1, broke booting on the
Raspberry Pi Compute Module 4.  Apparently 830aa6f2 panics with an
Asynchronous SError Interrupt, and after further commits here is a black
screen on HDMI and no output on the serial console.

This does not seem to affect the Raspberry Pi 4 B.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=215925
Link: https://lore.kernel.org/r/20220511201856.808690-3-helgaas@kernel.org


Reported-by: Cyril Brulebois <kibi@debian.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>