intel: add support for xglPinSystemMemory()

The updated kmd supports intel_winsys_import_userptr() for pinning.
diff --git a/icd/intel/gpu.c b/icd/intel/gpu.c
index 7baafbb..2605e80 100644
--- a/icd/intel/gpu.c
+++ b/icd/intel/gpu.c
@@ -284,9 +284,7 @@
                                 XGL_PHYSICAL_GPU_MEMORY_PROPERTIES *props)
 {
     props->supportsMigration = false;
-
-    /* no winsys support for DRM_I915_GEM_USERPTR yet */
-    props->supportsPinning = false;
+    props->supportsPinning = true;
 }
 
 int intel_gpu_get_max_threads(const struct intel_gpu *gpu,