ia64: io: implement dummy relaxed accessor macros for writes

write{b,w,l,q}_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 ia64, which may
be able to be optimised in a similar manner to the relaxed read
accessors at a later date.

Cc: Tony Luck <tony.luck@intel.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

arch/ia64/include/asm/io.h

@@ -393,6 +393,10 @@ __writeq (unsigned long val, volatile void __iomem *addr)
 #define writew(v,a)	__writew((v), (a))
 #define writel(v,a)	__writel((v), (a))
 #define writeq(v,a)	__writeq((v), (a))
+#define writeb_relaxed(v,a)	__writeb((v), (a))
+#define writew_relaxed(v,a)	__writew((v), (a))
+#define writel_relaxed(v,a)	__writel((v), (a))
+#define writeq_relaxed(v,a)	__writeq((v), (a))
 #define __raw_writeb	writeb
 #define __raw_writew	writew
 #define __raw_writel	writel