nvmf: add notice for virtual namespace additions

Match the direct NVMe device backend by printing out each block device
that is added as a namespace to a virtual subsystem.

Change-Id: I5c2762ca1fbab3529c19c822c95c73b72e9dabbc
Signed-off-by: Daniel Verkamp <daniel.verkamp@intel.com>

app/nvmf_tgt/conf.c

@@ -512,6 +512,10 @@ spdk_nvmf_parse_subsystem(struct spdk_conf_section *sp)
 				nvmf_delete_subsystem(subsystem);
 				return -1;
 			}
+
+			SPDK_NOTICELOG("Attaching block device %s to subsystem %s\n",
+				       bdev->name, subsystem->subnqn);
+
 		}
 	}
 	return 0;