bonding: show NS IPv6 targets in proc master info

When adding bond new parameter ns_targets. I forgot to print this
in bond master proc info. After updating, the bond master info will look
like:

ARP IP target/s (n.n.n.n form): 192.168.1.254
NS IPv6 target/s (XX::XX form): 2022::1, 2022::2

Fixes: 4e24be018eb9 ("bonding: add new parameter ns_targets")
Reported-by: Li Liang <[e-mail]>
Signed-off-by: Hangbin Liu <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Paolo Abeni <[e-mail]>

drivers/net/bonding/bond_procfs.c

···
 			printed = 1;
 		}
 		seq_printf(seq, "\n");
+
+#if IS_ENABLED(CONFIG_IPV6)
+		printed = 0;
+		seq_printf(seq, "NS IPv6 target/s (xx::xx form):");
+
+		for (i = 0; (i < BOND_MAX_NS_TARGETS); i++) {
+			if (ipv6_addr_any(&bond->params.ns_targets[i]))
+				break;
+			if (printed)
+				seq_printf(seq, ",");
+			seq_printf(seq, " %pI6c", &bond->params.ns_targets[i]);
+			printed = 1;
+		}
+		seq_printf(seq, "\n");
+#endif
 	}
 
 	if (BOND_MODE(bond) == BOND_MODE_8023AD) {