md: raid10: Fix compilation warning

Remove the if statement around the call to sysfs_link_rdev() in
raid10_start_reshape() to avoid the compilation warning:

warning: suggest braces around empty body in an ‘if’ statement

when compiling with W=1.
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Song Liu <songliubraving@fb.com>

drivers/md/raid10.c

@@ -4307,8 +4307,8 @@ static int raid10_start_reshape(struct mddev *mddev)
 					else
 						rdev->recovery_offset = 0;
 
-					if (sysfs_link_rdev(mddev, rdev))
-						/* Failure here  is OK */;
+					/* Failure here is OK */
+					sysfs_link_rdev(mddev, rdev);
 				}
 			} else if (rdev->raid_disk >= conf->prev.raid_disks
 				   && !test_bit(Faulty, &rdev->flags)) {