bonding: fix error checking in bond_debug_reregister()

Since commit ff9fb72b ("debugfs: return error values,
not NULL") changed return value of debugfs_rename() in
error cases from %NULL to %ERR_PTR(-ERROR), we should
also check error values instead of NULL.

Fixes: ff9fb72b ("debugfs: return error values, not NULL")
Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
Acked-by: Jay Vosburgh <jay.vosburgh@canonical.com>
Link: https://lore.kernel.org/r/20230202093256.32458-1-zhengqi.arch@bytedance.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/bonding/bond_debugfs.c

@@ -76,7 +76,7 @@ void bond_debug_reregister(struct bonding *bond)
 
 	d = debugfs_rename(bonding_debug_root, bond->debug_dir,
 			   bonding_debug_root, bond->dev->name);
-	if (d) {
+	if (!IS_ERR(d)) {
 		bond->debug_dir = d;
 	} else {
 		netdev_warn(bond->dev, "failed to reregister, so just unregister old one\n");