Wishlist: nvme-ns: allow specifying eui-64

UEFI device paths use the eui-64 property of the namespace to construct device paths. Two nvme namespaces can not coexist if they share the same eui-64. QEMU currently always uses 00-00-00-00-00-00-00-00.

The problem was already discussed in 2016: [Qemu-devel] [Bug 1529449] Re: serial is required for -device nvme