fs/ntfs3: Fix sparse warning for bigendian

Fixes: 220cf049 ("fs/ntfs3: Simplify initialization of $AttrDef and $UpCase")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202404181111.Wz8a1qX6-lkp@intel.com/Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>

fs/ntfs3/super.c

@@ -1491,11 +1491,10 @@ static int ntfs_fill_super(struct super_block *sb, struct fs_context *fc)
 
 #ifdef __BIG_ENDIAN
 	{
-		const __le16 *src = sbi->upcase;
 		u16 *dst = sbi->upcase;
 
 		for (i = 0; i < 0x10000; i++)
-			*dst++ = le16_to_cpu(*src++);
+			__swab16s(dst++);
 	}
 #endif