sch_cake: Add missing NLA policy entry TCA_CAKE_SPLIT_GSO

This field has never been checked since introduction in mainline kernel

Signed-off-by: Victorien Molle <victorien.molle@wifirst.fr>
Signed-off-by: Florent Fourcot <florent.fourcot@wifirst.fr>
Fixes: 2db6dc2 "sch_cake: Make gso-splitting configurable from userspace"
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sched/sch_cake.c

@@ -2184,6 +2184,7 @@ static const struct nla_policy cake_policy[TCA_CAKE_MAX + 1] = {
 	[TCA_CAKE_MPU]		 = { .type = NLA_U32 },
 	[TCA_CAKE_INGRESS]	 = { .type = NLA_U32 },
 	[TCA_CAKE_ACK_FILTER]	 = { .type = NLA_U32 },
+	[TCA_CAKE_SPLIT_GSO]	 = { .type = NLA_U32 },
 	[TCA_CAKE_FWMARK]	 = { .type = NLA_U32 },
 };