s390: move s390_pci_dma_ops to asm/pci_dma.h

This is not needed in drivers, so move it to a private header.
Signed-off-by: NChristoph Hellwig <hch@lst.de>

arch/s390/include/asm/dma-mapping.h

@@ -9,8 +9,6 @@
 #include <linux/dma-debug.h>
 #include <linux/io.h>
 
-extern const struct dma_map_ops s390_pci_dma_ops;
-
 static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)
 {
 	return &dma_noop_ops;

arch/s390/include/asm/pci_dma.h

@@ -201,4 +201,7 @@ void dma_cleanup_tables(unsigned long *);
 unsigned long *dma_walk_cpu_trans(unsigned long *rto, dma_addr_t dma_addr);
 void dma_update_cpu_trans(unsigned long *entry, void *page_addr, int flags);
 
+extern const struct dma_map_ops s390_pci_dma_ops;
+
+
 #endif