soft-off: ensure only one soft off service runs

OpenBMC has two implementations of the soft off function. This function
is utilized to tell the host to shutdown gracefully and for the BMC to
wait for that shutdown.

The implementation used depends on the interface being used to talk
with the host. There is the IPMI based interface and the new PLDM based
interface.

In theory, only one of these interfaces should be used to talk with the
host on a system. In reality there are some systems such as rainier
which are in the process of switching from IPMI to PLDM. In this case
both services for soft off are installed into the image.

Since this co-existence of both packages on a single system is a
temporary situation, put a simple change in which ensures the IPMI soft
off service does not run if the PLDM one is present. The assumption here
is that if the newer PLDM based package is installed, the system owner
prefers the PLDM soft off service be utilized.

(From meta-phosphor rev: 4c6e2c14a957111a7875eb03abb3121fab61f073)

Change-Id: If843f578590b99a90e53116f8cefc4065332e999
Signed-off-by: Andrew Geissler <geissonator@yahoo.com>
diff --git a/meta-phosphor/recipes-phosphor/ipmi/phosphor-ipmi-host/xyz.openbmc_project.Ipmi.Internal.SoftPowerOff.service b/meta-phosphor/recipes-phosphor/ipmi/phosphor-ipmi-host/xyz.openbmc_project.Ipmi.Internal.SoftPowerOff.service
index 600c86a..ce4c561 100644
--- a/meta-phosphor/recipes-phosphor/ipmi/phosphor-ipmi-host/xyz.openbmc_project.Ipmi.Internal.SoftPowerOff.service
+++ b/meta-phosphor/recipes-phosphor/ipmi/phosphor-ipmi-host/xyz.openbmc_project.Ipmi.Internal.SoftPowerOff.service
@@ -6,6 +6,7 @@
 Before=obmc-host-stopping@0.target
 Conflicts=obmc-host-start@0.target
 ConditionPathExists=!/run/openbmc/host@0-request
+ConditionPathExists=!/lib/systemd/system/pldmSoftPowerOff.service
 
 [Service]
 Restart=no