binding: update for pImmutableSamplers

v2: fix a typo in the type of shared_immutable_sampler (olv)
diff --git a/tests/xglrenderframework.cpp b/tests/xglrenderframework.cpp
index 005ef71..f5788b5 100644
--- a/tests/xglrenderframework.cpp
+++ b/tests/xglrenderframework.cpp
@@ -340,7 +340,7 @@
         bindings[i].descriptorType = m_type_counts[i].type;
         bindings[i].count = m_type_counts[i].count;
         bindings[i].stageFlags = XGL_SHADER_STAGE_FLAGS_ALL;
-        bindings[i].immutableSampler = XGL_NULL_HANDLE;
+        bindings[i].pImmutableSamplers = NULL;
     }
 
     // create XGL_DESCRIPTOR_SET_LAYOUT