sensorhandler: add missing pointer initialization

An uninitialized pointer was being sent to 'free' in cases where
a dbus object was not found to back a sensor.

Fixes openbmc/openbmc#1740.

Change-Id: Iaa62bfe460c47f4a51a506b0219879f0b6d46dd4
Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
1 file changed