Remove ThunderX PCIe FDT quirks from pci_host_generic_fdt.c

ThunderX is the only board known to use them.
Move them to the ThunderX PCIe driver.

Submitted by: Kornel Duleba <mindal@semihalf.com>
Reviewed by: andrew
Obtained from: Semihalf
Sponsored by: Alstom Group
Differential Revision: https://reviews.freebsd.org/D30179