Update ThunderX PCIe driver to fit new DTS layout

In recent EFI the DTS entries changed for PCIe controller.
This commit fixes internal PCIe, external is yet TBD.

Submitted by: Dominik Ermel <der@semihalf.com>
Obtained from: Semihalf
Sponsored by: The FreeBSD Foundation
Differential revision: https://reviews.freebsd.org/D4976