Move remaining GPU logic into modify pod hook

To have all GPU-related logic together in the modify pod hook for
computing resources.

swan-cern/files/swan_computing_config.py

@@ -124,6 +124,15 @@ def _modify_pod_for_gpu(self):
         resources.requests[gpu_resource_name] = '1'
         resources.limits[gpu_resource_name] = '1'
 
+        # Configure OpenCL to use NVIDIA backend
+        notebook_container.env = self._add_or_replace_by_name(
+            notebook_container.env,
+            V1EnvVar(
+                name='OCL_ICD_FILENAMES',
+                value='libnvidia-opencl.so.1'
+            ),
+        )
+
     async def _init_hadoop_secret(self):
         """
         Create secret for Spark/Hadoop
@@ -267,7 +276,7 @@ def _gpu_enabled(self):
         """
         return True if the user has requested a GPU
         """
-        return self.spawner.gpu_requested()
+        return "cu" in self.spawner.user_options[self.spawner.lcg_rel_field]
 
     def _spark_enabled(self):
         """