icd: Make driver use the same definition for dispatch table as loader uses

Loader and icd were using two different structs to define dispatch table.
Consolidate to to use the dispatch table defined in xglLayer.h so we
will not have issues with them getting out of sync.
diff --git a/icd/intel/gpu.h b/icd/intel/gpu.h
index 4ed336a..39bdf32 100644
--- a/icd/intel/gpu.h
+++ b/icd/intel/gpu.h
@@ -55,7 +55,7 @@
  * intel_gpu is the only object that does not inherit from intel_base.
  */
 struct intel_gpu {
-    const struct icd_dispatch_table *dispatch;
+    const XGL_LAYER_DISPATCH_TABLE *dispatch;
 
     struct intel_gpu *next;