Conditionally log a DeviceGroupedConvBwdWeightTwoStage_Xdl_CShuffle warning (#1860)

The code was emitting a warning if MIOpen did not create a workspace
prior to invoking the IsSupportedArgument method, but the
condition for MIOpen to create a workspace was not met, and so this
condition was not really an error but more of a log message.  This commit
addresses this issue by using the CK_LOGGING facility to only generate the
log message if the CK_LOGGING environment variable is set.

include/ck/tensor_operation/gpu/device/impl/device_grouped_conv_bwd_weight_two_stage_xdl_cshuffle.hpp

@@ -1495,10 +1495,13 @@ struct DeviceGroupedConvBwdWeightTwoStage_Xdl_CShuffle
         // if workspace is not allocated
         if(!arg.p_workspace_)
         {
-            std::cerr << "Warning: Workspace for "
+            if(ck::EnvIsEnabled(CK_ENV(CK_LOGGING)))
+            {
+                std::cout << "Warning: Workspace for "
                              "DeviceGroupedConvBwdWeightTwoStage_Xdl_CShuffle::Argument is not "
                              "allocated, use SetWorkSpacePointer."
                           << std::endl;
+            }
             return false;
         }
         if(!ck::is_xdl_supported())