bonding: correctly handle out of range parameters for lp_interval

We didn't correctly check cases where the value for lp_interval is not
within the legal range due to a missing table terminator.

This would let userspace trigger a kernel panic by specifying a value out
of range:

	echo -1 > /sys/devices/virtual/net/bond0/bonding/lp_interval

Introduced by commit 4325b374 ("bonding: convert lp_interval to use
the new option API").
Acked-by: NNikolay Aleksandrov <nikolay@redhat.com>
Signed-off-by: NSasha Levin <sasha.levin@oracle.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/bonding/bond_options.c

@@ -121,6 +121,7 @@ static struct bond_opt_value bond_resend_igmp_tbl[] = {
 static struct bond_opt_value bond_lp_interval_tbl[] = {
 	{ "minval",  1,       BOND_VALFLAG_MIN | BOND_VALFLAG_DEFAULT},
 	{ "maxval",  INT_MAX, BOND_VALFLAG_MAX},
+	{ NULL,      -1,      0},
 };
 
 static struct bond_option bond_opts[] = {