alpha: io: define ioremap_uc

ioremap_uc was not defined and as a result while building with
allmodconfig were getting build error of: implicit declaration of
function 'ioremap_uc'.

Signed-off-by: Sudip Mukherjee <[e-mail]>
Cc: Richard Henderson <[e-mail]>
Cc: Ivan Kokshaysky <[e-mail]>
Cc: Matt Turner <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

arch/alpha/include/asm/io.h

···
 					     unsigned long size)
 {
 	return ioremap(offset, size);
-} 
+}
+
+#define ioremap_uc ioremap_nocache
 
 static inline void iounmap(volatile void __iomem *addr)
 {