cris: io: implement dummy relaxed accessor macros for writes

write{b,w,l}_relaxed are implemented by some architectures in order to
permit memory-mapped I/O accesses with weaker barrier semantics than the
non-relaxed variants.

This patch adds dummy macros for the write accessors to Cris, in the same
vein as the dummy definitions for the relaxed read accessors.

Cc: Mikael Starvik <starvik@axis.com>
Acked-by: NJesper Nilsson <jesper.nilsson@axis.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

arch/cris/include/asm/io.h

@@ -112,6 +112,9 @@ static inline void writel(unsigned int b, volatile void __iomem *addr)
 	else
 		*(volatile unsigned int __force *) addr = b;
 }
+#define writeb_relaxed(b, addr) writeb(b, addr)
+#define writew_relaxed(b, addr) writew(b, addr)
+#define writel_relaxed(b, addr) writel(b, addr)
 #define __raw_writeb writeb
 #define __raw_writew writew
 #define __raw_writel writel