Blackfin arch: cleanup IO and DMA_IO API function definitions according to other arches

Signed-off-by: Bryan Wu <bryan.wu@analog.com>

diff --git a/arch/blackfin/kernel/bfin_dma_5xx.c b/arch/blackfin/kernel/bfin_dma_5xx.c
index f0db6c5..858cca6 100644
--- a/arch/blackfin/kernel/bfin_dma_5xx.c
+++ b/arch/blackfin/kernel/bfin_dma_5xx.c
@@ -583,7 +583,7 @@
 }
 EXPORT_SYMBOL(safe_dma_memcpy);
 
-void dma_outsb(void __iomem *addr, const void *buf, unsigned short len)
+void dma_outsb(const void __iomem *addr, const void *buf, unsigned short len)
 {
 	unsigned long flags;
 
@@ -647,7 +647,7 @@
 }
 EXPORT_SYMBOL(dma_insb);
 
-void dma_outsw(void __iomem *addr, const void  *buf, unsigned short len)
+void dma_outsw(const void __iomem *addr, const void  *buf, unsigned short len)
 {
 	unsigned long flags;
 
@@ -711,7 +711,7 @@
 }
 EXPORT_SYMBOL(dma_insw);
 
-void dma_outsl(void __iomem *addr, const void *buf, unsigned short len)
+void dma_outsl(const void __iomem *addr, const void *buf, unsigned short len)
 {
 	unsigned long flags;
 
diff --git a/include/asm-blackfin/io.h b/include/asm-blackfin/io.h
index 142cb33..3f48f8f 100644
--- a/include/asm-blackfin/io.h
+++ b/include/asm-blackfin/io.h
@@ -115,17 +115,17 @@
 
 #ifndef __ASSEMBLY__
 
-extern void outsb(void __iomem *port, const void *addr, unsigned short count);
-extern void outsw(void __iomem *port, const void *addr, unsigned short count);
-extern void outsl(void __iomem *port, const void *addr, unsigned short count);
+extern void outsb(const void __iomem *port, const void *addr, unsigned short count);
+extern void outsw(const void __iomem *port, const void *addr, unsigned short count);
+extern void outsl(const void __iomem *port, const void *addr, unsigned short count);
 
 extern void insb(const void __iomem *port, void *addr, unsigned short count);
 extern void insw(const void __iomem *port, void *addr, unsigned short count);
 extern void insl(const void __iomem *port, void *addr, unsigned short count);
 
-extern void dma_outsb(void __iomem *port, const void *addr, unsigned short count);
-extern void dma_outsw(void __iomem *port, const void *addr, unsigned short count);
-extern void dma_outsl(void __iomem *port, const void *addr, unsigned short count);
+extern void dma_outsb(const void __iomem *port, const void *addr, unsigned short count);
+extern void dma_outsw(const void __iomem *port, const void *addr, unsigned short count);
+extern void dma_outsl(const void __iomem *port, const void *addr, unsigned short count);
 
 extern void dma_insb(const void __iomem *port, void *addr, unsigned short count);
 extern void dma_insw(const void __iomem *port, void *addr, unsigned short count);