When using IOPORT with pci_host_generic we are missing setting the rman_end()

which leads to end being before start and thus a signed extended very large
number of size later on, which kva_alloc() will fail upon and we will panic.
Add the missing call.

Debugged with:	andrew
Reviewed by:	br, andrew
Sponsored by:	DARPA/AFRL
Found:		while using virtio with gem5
MFC after:	2 weeks
Differential Revision:	https://reviews.freebsd.org/D6337

sys/dev/pci/pci_host_generic.c

@@ -613,6 +613,7 @@ generic_pcie_activate_resource(device_t dev, device_t child, int type, int rid,
 		}
 		if (found) {
 			rman_set_start(r, rman_get_start(r) + phys_base);
+			rman_set_end(r, rman_get_end(r) + phys_base);
 			BUS_ACTIVATE_RESOURCE(device_get_parent(dev), child,
 						type, rid, r);
 		} else {