[MIPS] Workaround for a sparse warning in include/asm-mips/io.h

CKSEG1ADDR() returns unsigned int value on 32bit kernel.  Cast it to
unsigned long to get rid of this warning:

include2/asm/io.h:215:12: warning: cast adds address space to expression (<asn:2>)
Signed-off-by: NAtsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

include/asm-mips/io.h

@@ -212,7 +212,8 @@ static inline void __iomem * __ioremap_mode(phys_t offset, unsigned long size,
 		 */
 		if (__IS_LOW512(phys_addr) && __IS_LOW512(last_addr) &&
 		    flags == _CACHE_UNCACHED)
-			return (void __iomem *)CKSEG1ADDR(phys_addr);
+			return (void __iomem *)
+				(unsigned long)CKSEG1ADDR(phys_addr);
 	}
 
 	return __ioremap(offset, size, flags);