[Decode] Scalability reg key not work

Reg key unable to disable decode scalability
diff --git a/media_driver/media_interface/media_interfaces_dg2/media_interfaces_dg2.cpp b/media_driver/media_interface/media_interfaces_dg2/media_interfaces_dg2.cpp
index 0b275df..fdeb263 100644
--- a/media_driver/media_interface/media_interfaces_dg2/media_interfaces_dg2.cpp
+++ b/media_driver/media_interface/media_interfaces_dg2/media_interfaces_dg2.cpp
@@ -572,7 +572,7 @@
 
     if (CodecHalIsDecode(CodecFunction))
     {
-        if(osInterface->bHcpDecScalabilityMode = MOS_SCALABILITY_ENABLE_MODE_USER_FORCE)
+        if(osInterface->bHcpDecScalabilityMode == MOS_SCALABILITY_ENABLE_MODE_USER_FORCE)
         {
             disableScalability = false;
         }