MIPS: AR7: Fix build warning on memory.c

This patch fixes the following build warning:
arch/mips/ar7/memory.c: In function 'memsize':
arch/mips/ar7/memory.c:55: warning: passing argument 1 of 'writel' makes integer from pointer without a cast
Signed-off-by: NFlorian Fainelli <florian@openwrt.org>
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

arch/mips/ar7/memory.c

@@ -52,7 +52,7 @@ static int __init memsize(void)
 		size <<= 1;
 	} while (size < (64 << 20));
 
-	writel(tmpaddr, &addr);
+	writel((u32)tmpaddr, &addr);
 
 	return size;
 }