nfp: flower: fix incorrect struct type in GRE key_size

Looks like a copy-paste error sneaked in here at some point,
causing the key_size for these tunnels to be calculated
incorrectly. This size ends up being send to the firmware,
causing unexpected behaviour in some cases.

Fixes: 78a722af ("nfp: flower: compile match for IPv6 tunnels")
Reported-by: Chaoyong He <chaoyong.he@corigine.com>
Signed-off-by: Louis Peens <louis.peens@corigine.com>
Signed-off-by: Simon Horman <simon.horman@corigine.com>
Link: https://lore.kernel.org/r/20221007092132.218386-1-simon.horman@corigine.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/netronome/nfp/flower/offload.c

@@ -373,10 +373,10 @@ nfp_flower_calculate_key_layers(struct nfp_app *app,
 			if (ipv6_tun) {
 				key_layer_two |= NFP_FLOWER_LAYER2_TUN_IPV6;
 				key_size +=
-					sizeof(struct nfp_flower_ipv6_udp_tun);
+					sizeof(struct nfp_flower_ipv6_gre_tun);
 			} else {
 				key_size +=
-					sizeof(struct nfp_flower_ipv4_udp_tun);
+					sizeof(struct nfp_flower_ipv4_gre_tun);
 			}
 
 			if (enc_op.key) {