s390: remove the ptep_modify_prot_{start,commit} exports

These two functions are only used by core MM code, so no need to export
them.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/mm/pgtable.c

@@ -318,7 +318,6 @@ pte_t ptep_modify_prot_start(struct mm_struct *mm, unsigned long addr,
 	}
 	return old;
 }
-EXPORT_SYMBOL(ptep_modify_prot_start);
 
 void ptep_modify_prot_commit(struct mm_struct *mm, unsigned long addr,
 			     pte_t *ptep, pte_t pte)
@@ -337,7 +336,6 @@ void ptep_modify_prot_commit(struct mm_struct *mm, unsigned long addr,
 	}
 	preempt_enable();
 }
-EXPORT_SYMBOL(ptep_modify_prot_commit);
 
 static inline void pmdp_idte_local(struct mm_struct *mm,
 				   unsigned long addr, pmd_t *pmdp)