Release the pinned pages

HySoP/hysop/gpu/multi_gpu_particle_advection.py

@@ -690,6 +690,8 @@ class MultiGPUParticleAdvection(GPUParticleAdvection):
         Cleaning, if required.
         """
         super(MultiGPUParticleAdvection, self).finalize()
+        self._s_l_buff.base.release(self.cl_env.queue)
+        self._s_r_buff.base.release(self.cl_env.queue)
         # if self._is_cut_dir:
         #     s = 0
         #     for w in [self._cl_v_r_buff, self._cl_v_l_buff,