s390/mm: use generic mm_hooks

With git commit 3446c13b
"s390/mm: four page table levels vs. fork"
s390 dropped its architecture specific version of arch_dup_mmap.

Now all functions defined by include/asm-generic/mm_hooks.h are
identical to the s390 versions. Use the generic header.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/include/asm/mmu_context.h

@@ -12,6 +12,7 @@
 #include <linux/mm_types.h>
 #include <asm/tlbflush.h>
 #include <asm/ctl_reg.h>
+#include <asm-generic/mm_hooks.h>
 
 static inline int init_new_context(struct task_struct *tsk,
 				   struct mm_struct *mm)
@@ -133,30 +134,4 @@ static inline void activate_mm(struct mm_struct *prev,
 	set_user_asce(next);
 }
 
-static inline void arch_dup_mmap(struct mm_struct *oldmm,
-				 struct mm_struct *mm)
-{
-}
-
-static inline void arch_exit_mmap(struct mm_struct *mm)
-{
-}
-
-static inline void arch_unmap(struct mm_struct *mm,
-			struct vm_area_struct *vma,
-			unsigned long start, unsigned long end)
-{
-}
-
-static inline void arch_bprm_mm_init(struct mm_struct *mm,
-				     struct vm_area_struct *vma)
-{
-}
-
-static inline bool arch_vma_access_permitted(struct vm_area_struct *vma,
-		bool write, bool execute, bool foreign)
-{
-	/* by default, allow everything */
-	return true;
-}
 #endif /* __S390_MMU_CONTEXT_H */