intel: do not advertise pinning

Not needed for now.
diff --git a/icd/intel/gpu.c b/icd/intel/gpu.c
index 8799f62..eb04e1a 100644
--- a/icd/intel/gpu.c
+++ b/icd/intel/gpu.c
@@ -289,7 +289,8 @@
     /* no kernel support yet */
     props->supportsVirtualMemoryRemapping = false;
 
-    props->supportsPinning = true;
+    /* no winsys support for DRM_I915_GEM_USERPTR yet */
+    props->supportsPinning = false;
 }
 
 XGL_RESULT intel_gpu_open(struct intel_gpu *gpu)