make pldmd a dbus systemd service

With the introduction of PLDM supporting the new
xyz.openbmc_project.Condition.HostFirmware interface and other services
depending on that interface being on D-Bus, it's time to convert the
pldmd service to a D-Bus service.

This allows other services to put a "After=pldmd" in their service and
be assured that pldmd has put its service on the bus before the service
is considered done.

Tested:
- Verified with the other "bmc-reset-host-up" commits that this fixed a
  synchronization issue between phosphor-state-manager and pldmd.

Signed-off-by: Andrew Geissler <geissonator@yahoo.com>
Change-Id: I1fa7630f8ef72c5361e3dab983e5096e1cdfebd3
diff --git a/pldmd/service_files/pldmd.service b/pldmd/service_files/pldmd.service
index f55012f..4eaa706 100644
--- a/pldmd/service_files/pldmd.service
+++ b/pldmd/service_files/pldmd.service
@@ -5,6 +5,8 @@
 
 [Service]
 Restart=always
+Type=dbus
+BusName=xyz.openbmc_project.PLDM
 EnvironmentFile=/etc/default/pldm_verbosity
 ExecStart=/usr/bin/pldmd --verbose $VERBOSE