Sensor.Value: add defaults for min/max

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I059ecabe4c02fc9decc08ce403d78ca34b25abf6
diff --git a/xyz/openbmc_project/Sensor/Value.interface.yaml b/xyz/openbmc_project/Sensor/Value.interface.yaml
index c9b4a55..1062105 100644
--- a/xyz/openbmc_project/Sensor/Value.interface.yaml
+++ b/xyz/openbmc_project/Sensor/Value.interface.yaml
@@ -24,10 +24,12 @@
           The sensor reading.
     - name: MaxValue
       type: double
+      default: infinity
       description: >
           The Maximum supported sensor reading.
     - name: MinValue
       type: double
+      default: -infinity
       description: >
           The Minimum supported sensor reading.
     - name: Unit