Fix MaxConcurrentSessions property of GraphicalConsole

Now we support up to 4 concurrent KVM sessions so this commit fixes
'MaxConcurrentSessions' property of 'GraphicalConsole'.

Change-Id: Id225247dcb2d0b884a8a41253863294385268585
Signed-off-by: Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com>
diff --git a/redfish-core/lib/managers.hpp b/redfish-core/lib/managers.hpp
index 12ed177..459edad 100644
--- a/redfish-core/lib/managers.hpp
+++ b/redfish-core/lib/managers.hpp
@@ -1591,7 +1591,7 @@
 #ifdef BMCWEB_ENABLE_KVM
         // Fill in GraphicalConsole info
         res.jsonValue["GraphicalConsole"]["ServiceEnabled"] = true;
-        res.jsonValue["GraphicalConsole"]["MaxConcurrentSessions"] = 1;
+        res.jsonValue["GraphicalConsole"]["MaxConcurrentSessions"] = 4;
         res.jsonValue["GraphicalConsole"]["ConnectTypesSupported"] = {"KVMIP"};
 #endif // BMCWEB_ENABLE_KVM