Some PCIe devices on the M1 and M1 Pro/Max need to be explicitly powered on

Some PCIe devices on the M1 and M1 Pro/Max need to be explicitly powered on
(most notably the WiFi chip).  This is done through a GPIO controlled by
the SMC.  Add support for this and make sure we wait for the 100ms required
by the PCIe standard when we use that GPIO to turn on power.  This makes sure
these devices are available even if U-Boot doesn't turn them on for us.

ok patrick@