sw64: lib: fix __iowrite64_copy()

Sunway inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I56OLG

--------------------------------

The mb() is supposed to be in the loop as what __iowrite32_copy()
does. Besides, CONFIG_64BIT is always true for SW64, so remove the
redundant #if statement.
Signed-off-by: NDai Xin <daixin@wxiat.com>
Signed-off-by: NGu Zitao <guzitao@wxiat.com>

arch/sw_64/lib/iomap_copy.c

@@ -41,15 +41,12 @@ void __iowrite64_copy(void __iomem *to,
 		      const void *from,
 		      size_t count)
 {
-#ifdef CONFIG_64BIT
 	u64 __iomem *dst = to;
 	const u64 *src = from;
 	const u64 *end = src + count;
 
-	while (src < end)
+	while (src < end) {
 		__raw_writeq(*src++, dst++);
 		mb();
-#else
-	__iowrite32_copy(to, from, count * 2);
-#endif
+	}
 }