Fix failure in reading power value during PowerOff state
Fix failure in reading power value during PowerOff state

D-Bus sensor object to read power value is not created during
PowerOff state. Fixed to return 0 power value if sensor object
is not present.

Change-Id: Ibe340cab0483c7a711081197b932aaba0408d333
Signed-off-by: Marri Devender Rao <0a3dc38878bb7754216ba1e690ff81eb9075b092@in.ibm.com>

openbmc/phosphor-host-ipmid,openbmc/phosphor-host-ipmid,openbmc/phosphor-host-ipmid