storagecommands: fix sensorTree never updated

Swap the sequence of sensorTree.empty() and getSensorSubtree() in if
statement.
This will fix the issue of sensorTree never get updated.

Change-Id: I225c3641145643ef481aec977ebd4b8b277b2dc8
Signed-off-by: Potin Lai <potin.lai@quantatw.com>
diff --git a/src/storagecommands.cpp b/src/storagecommands.cpp
index 532549a..cf66413 100644
--- a/src/storagecommands.cpp
+++ b/src/storagecommands.cpp
@@ -601,7 +601,7 @@
         return IPMI_CC_INVALID_RESERVATION_ID;
     }
 
-    if (sensorTree.empty() && !getSensorSubtree(sensorTree))
+    if (!getSensorSubtree(sensorTree) && sensorTree.empty())
     {
         return IPMI_CC_RESPONSE_ERROR;
     }
@@ -823,7 +823,7 @@
 static int getSensorConnectionByName(std::string& name, std::string& connection,
                                      std::string& path)
 {
-    if (sensorTree.empty() && !getSensorSubtree(sensorTree))
+    if (!getSensorSubtree(sensorTree) && sensorTree.empty())
     {
         return -1;
     }