macsec: add missing attribute validation for offload

Add missing attribute validation for IFLA_MACSEC_OFFLOAD
to the netlink policy.

Fixes: 791bb3fc ("net: macsec: add support for specifying offload upon link creation")
Signed-off-by: Emeel Hakim <ehakim@nvidia.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Link: https://lore.kernel.org/r/20221207101618.989-1-ehakim@nvidia.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/macsec.c

@@ -3698,6 +3698,7 @@ static const struct nla_policy macsec_rtnl_policy[IFLA_MACSEC_MAX + 1] = {
 	[IFLA_MACSEC_SCB] = { .type = NLA_U8 },
 	[IFLA_MACSEC_REPLAY_PROTECT] = { .type = NLA_U8 },
 	[IFLA_MACSEC_VALIDATION] = { .type = NLA_U8 },
+	[IFLA_MACSEC_OFFLOAD] = { .type = NLA_U8 },
 };
 
 static void macsec_free_netdev(struct net_device *dev)