"hw.physmem" only reports reasonable results on 32 bit systems and is
kept to not break binary compatibility. On other systems, it reports
"-1". "hw.phymem64" reports reasonable results on all systems.
MinIO getHwPhysmem method currently uses the deprecated
"hw.physmem" key which results in a parse error (due to the -1).
This pull request asks for changing this. The change was tested
successfully on NetBSD/amd64 9.1.
