Revert "BACKPORT: FROMGIT: Mark anonymous struct field of 'struct vm_fault' as 'const'"

GCC generates an error because of this change. It seems one of those
things either LLVM or GCC can compile :-/

This reverts commit ccdd6170.

include/linux/mm.h

@@ -521,7 +521,7 @@ struct vm_fault {
 	unsigned int sequence;
 	pmd_t orig_pmd;			/* value of PMD at the time of fault */
 #endif
-	const struct {
+	struct {
 		struct vm_area_struct *vma;	/* Target VMA */
 		gfp_t gfp_mask;			/* gfp mask to be used for allocations */
 		pgoff_t pgoff;			/* Logical page offset based on vma */