Remove check for 64-bit FDT ranges in pci-host-generic

This allows 32-bit platforms to use pci-host-generic.

Obtained from: Semihalf
Submitted by: Michal Stanek <mst@semihalf.com>
Sponsored by: Annapurna Labs
Reviewed by: wma
Differential Revision: https://reviews.freebsd.org/D7560