[i.MX8MP/Linux 5.4.70.2.3.0]PCIE device power manager

[#1]

Platform: i.MX8MP

SW:Linux 5.4.70.2.3.0

On current linux BSP, PCIE driver does not support Hot-plug, customers wants to turn off PCIE device to save power, attached is guide.

1. Remove PCIE device driver
2. Suspend PCIE driver
3. Turn off PCIE device power supply
4. Turn on PCIE device power supply
5. Resume PCIE driver
6. Rescan PCIE device
7. Load PCIE device driver