Update D-Bus names per design

- Single-host service and object are named PostCode0. Multi-host service
  name does not comply with design but presumably it will be fixed in
  the future.

Tested: With
phosphor-host-postd: I89ab5f2eef7eab59823df3a063414f3ca3b2949f
bmcweb: I2fdf97b7aaf8d6471d162f8ed1b72143491ac23f
Power cycled host and verified that new POST codes are added under
/redfish/v1/Systems/system/LogServices/PostCodes/Entries.

Signed-off-by: Jonathan Doman <jonathan.doman@intel.com>
Change-Id: I59ed514f28c2bb9b159f51367c38557bf55bf226
diff --git a/service_files/xyz.openbmc_project.State.Boot.PostCode.service b/service_files/xyz.openbmc_project.State.Boot.PostCode.service
index 4246472..35ffd1f 100644
--- a/service_files/xyz.openbmc_project.State.Boot.PostCode.service
+++ b/service_files/xyz.openbmc_project.State.Boot.PostCode.service
@@ -2,10 +2,10 @@
 Description=Post code manager
 
 [Service]
-ExecStart=/usr/bin/env post-code-manager
+ExecStart=/usr/bin/post-code-manager --host 0
 SyslogIdentifier=post-code-manager
 Type=dbus
-BusName=xyz.openbmc_project.State.Boot.PostCode
+BusName=xyz.openbmc_project.State.Boot.PostCode0
 
 [Install]
 WantedBy=multi-user.target