s390/mm: introduce ptep_flush_lazy helper

Isolate the logic of IDTE vs. IPTE flushing of ptes in two functions,
ptep_flush_lazy and __tlb_flush_mm_lazy.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/include/asm/tlb.h b/arch/s390/include/asm/tlb.h
index 6d6d92b..2cb846c 100644
--- a/arch/s390/include/asm/tlb.h
+++ b/arch/s390/include/asm/tlb.h
@@ -63,13 +63,14 @@
 
 static inline void tlb_flush_mmu(struct mmu_gather *tlb)
 {
+	__tlb_flush_mm_lazy(tlb->mm);
 	tlb_table_flush(tlb);
 }
 
 static inline void tlb_finish_mmu(struct mmu_gather *tlb,
 				  unsigned long start, unsigned long end)
 {
-	tlb_table_flush(tlb);
+	tlb_flush_mmu(tlb);
 }
 
 /*