Undo accidental commit to omp-grid.c

The following change accidentally got committed in the previous
commit, r10-7614-g13e41d8b,
among the intended changes. Hence:

Revert:
	gcc/
	* omp-grid.c (grid_eliminate_combined_simd_part): Use
	OMP_CLAUSE_CODE to access the omp clause code.

gcc/omp-grid.c

@@ -1065,7 +1065,7 @@ grid_eliminate_combined_simd_part (gomp_for *parloop)
   while (*pc)
     {
       tree c = *pc;
-      switch (OMP_CLAUSE_CODE (c))
+      switch (TREE_CODE (c))
 	{
 	case OMP_CLAUSE_LINEAR:
 	  {