pid: fix zone string length

Should be 8 based on comment.

Tested: Updated patch script using latest zones
and it worked.

Example:
/redfish/v1/Managers/bmc#/Oem/OpenBmc/Fan/FanZones/Left

Change-Id: Ia56bc6ed4f02a05e91d3638c5b7f470f90d6eba4
Signed-off-by: James Feist <james.feist@linux.intel.com>
diff --git a/redfish-core/lib/managers.hpp b/redfish-core/lib/managers.hpp
index f9c2f38..3cde0ef 100644
--- a/redfish-core/lib/managers.hpp
+++ b/redfish-core/lib/managers.hpp
@@ -501,7 +501,11 @@
             return false;
         }
         std::string input;
-        if (!dbus::utility::getNthStringFromPath(path, 4, input))
+
+        // 8 below comes from
+        // /redfish/v1/Managers/bmc#/Oem/OpenBmc/Fan/FanZones/Left
+        //     0    1     2      3    4    5      6     7      8
+        if (!dbus::utility::getNthStringFromPath(path, 8, input))
         {
             BMCWEB_LOG_ERROR << "Got invalid path " << path;
             BMCWEB_LOG_ERROR << "Illegal Type Zones";