how to implement a custom nvmf_generate_discovery_log() function in libspdk_nvmf for DS

[majianpeng]

In https://github.com/ceph/ceph-nvmeof/issues/63 and https://github.com/ceph/ceph-nvmeof/issues/68, We discussed the rationale for host-specific discovery responses. We need a custom nvmf_generate_discovery_log() function.

[PepperJo]

My understanding is that we are not longer trying to implement discovery with SPDK so can you @majianpeng please go ahead and close all old issues related to implementing discovery with SPDK. Thank you!