block, dax: use correct format string in bdev_dax_supported

The new message has an incorrect format string, causing a warning in some
configurations:

fs/block_dev.c: In function 'bdev_dax_supported':
fs/block_dev.c:779:5: error: format '%d' expects argument of type 'int', but argument 2 has type 'long int' [-Werror=format=]
     "error: dax access failed (%d)", len);

This changes it to use the correct %ld instead of %d.

Fixes: 2093f2e9dfec ("block, dax: convert bdev_dax_supported() to dax_direct_access()")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

fs/block_dev.c

@@ -776,7 +776,7 @@ int bdev_dax_supported(struct super_block *sb, int blocksize)
 
 	if (len < 1) {
 		vfs_msg(sb, KERN_ERR,
-				"error: dax access failed (%d)", len);
+				"error: dax access failed (%ld)", len);
 		return len < 0 ? len : -EIO;
 	}