Match Marvell Armada38X PCI compatible with Linux

In Linux FDT pcie does not have compatible string.
Configuration of windows in mv_common was based on fdt compatible.
Now pcie windows are configured by their parent: pcie_controller.
Processing is moved to fdt_win_process_child. fdt_win_process now
only walk through the tree. SOC_NODE_PCI is position of pcie function in
soc_node_spec array.

PCIe probe cannot use ofw_bus_search_compatible, because it needs to
check also device type and parents compatible.

Submitted by: Rafal Kozik <rk@semihalf.com>
Reviewed by: manu [DT part]
Obtained from: Semihalf
Sponsored by: Stormshield
Differential Revision: https://reviews.freebsd.org/D14749