PCI DEN0115: Reliably check for a memory resource during probe.

rid was stack garbage, so the bus_alloc_resource_any() call could fail
and fall through to the SMCCC version check even if a bridge had a
memory resource.

Debugging help: jrtc27
Reviewed by: jrtc27
Fixes: c9a05c072270 Add a PCI driver that follows the Arm DEN0115 spec
Sponsored by: DARPA
Differential Revision: https://reviews.freebsd.org/D41025