Introduce new, common PCIe setup code for QC/A WiSoCs

Introduce new, common PCIe setup code for QC/A WiSoCs

New code setups PCIe PLL and resets PCIe controller.
For now, it was tested only on real hardware based
on QCA9531 and AR9344.

For information purposes, include also new line in
board info message, with vendor and device ID of
device/s connected on PCIe bus/es.