dma-mapping: move arch_dma_set_mask() declaration to header

This function has a __weak definition and an override that is only used on
freescale powerpc chips. The powerpc definition however does not see the
declaration that is in a .c file:

arch/powerpc/kernel/dma-mask.c:7:6: error: no previous prototype for 'arch_dma_set_mask' [-Werror=missing-prototypes]

Move it into the linux/dma-map-ops.h header where the other arch_dma_* functions
are declared.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>

arch/powerpc/kernel/dma-mask.c

 // SPDX-License-Identifier: GPL-2.0
 
 #include <linux/dma-mapping.h>
+#include <linux/dma-map-ops.h>
 #include <linux/export.h>
 #include <asm/machdep.h>
 

include/linux/dma-map-ops.h

@@ -343,6 +343,12 @@ void *arch_dma_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,
 void arch_dma_free(struct device *dev, size_t size, void *cpu_addr,
 		dma_addr_t dma_addr, unsigned long attrs);
 
+#ifdef CONFIG_ARCH_HAS_DMA_SET_MASK
+void arch_dma_set_mask(struct device *dev, u64 mask);
+#else
+#define arch_dma_set_mask(dev, mask)	do { } while (0)
+#endif
+
 #ifdef CONFIG_MMU
 /*
  * Page protection so that devices that can't snoop CPU caches can use the

kernel/dma/mapping.c

@@ -760,12 +760,6 @@ bool dma_pci_p2pdma_supported(struct device *dev)
 }
 EXPORT_SYMBOL_GPL(dma_pci_p2pdma_supported);
 
-#ifdef CONFIG_ARCH_HAS_DMA_SET_MASK
-void arch_dma_set_mask(struct device *dev, u64 mask);
-#else
-#define arch_dma_set_mask(dev, mask)	do { } while (0)
-#endif
-
 int dma_set_mask(struct device *dev, u64 mask)
 {
 	/*