alpha: Define ioremap_wc

Commit 3cc2dac5 ("drivers/video/fbdev/atyfb: Replace MTRR UC hole
with strong UC") introduces calls to ioremap_wc and ioremap_uc. This
causes build failures with alpha:allmodconfig. Map the missing functions
to ioremap_nocache.

Fixes: 3cc2dac5 ("drivers/video/fbdev/atyfb:
        Replace MTRR UC hole with strong UC")
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Luis R. Rodriguez <mcgrof@suse.com>
Signed-off-by: NGuenter Roeck <linux@roeck-us.net>
Signed-off-by: NMatt Turner <mattst88@gmail.com>

arch/alpha/include/asm/io.h

@@ -299,6 +299,7 @@ static inline void __iomem * ioremap_nocache(unsigned long offset,
 	return ioremap(offset, size);
 }
 
+#define ioremap_wc ioremap_nocache
 #define ioremap_uc ioremap_nocache
 
 static inline void iounmap(volatile void __iomem *addr)