net/core: move gro function declarations to separate header

Fir the following compilation warnings:
 1031 | INDIRECT_CALLABLE_SCOPE void udp_v6_early_demux(struct sk_buff *skb)

net/ipv6/ip6_offload.c:182:41: warning: no previous prototype for ‘ipv6_gro_receive’ [-Wmissing-prototypes]
  182 | INDIRECT_CALLABLE_SCOPE struct sk_buff *ipv6_gro_receive(struct list_head *head,
      |                                         ^~~~~~~~~~~~~~~~
net/ipv6/ip6_offload.c:320:29: warning: no previous prototype for ‘ipv6_gro_complete’ [-Wmissing-prototypes]
  320 | INDIRECT_CALLABLE_SCOPE int ipv6_gro_complete(struct sk_buff *skb, int nhoff)
      |                             ^~~~~~~~~~~~~~~~~
net/ipv6/ip6_offload.c:182:41: warning: no previous prototype for ‘ipv6_gro_receive’ [-Wmissing-prototypes]
  182 | INDIRECT_CALLABLE_SCOPE struct sk_buff *ipv6_gro_receive(struct list_head *head,
      |                                         ^~~~~~~~~~~~~~~~
net/ipv6/ip6_offload.c:320:29: warning: no previous prototype for ‘ipv6_gro_complete’ [-Wmissing-prototypes]
  320 | INDIRECT_CALLABLE_SCOPE int ipv6_gro_complete(struct sk_buff *skb, int nhoff)
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

include/net/gro.h

+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#ifndef _NET_IPV6_GRO_H
+#define _NET_IPV6_GRO_H
+
+INDIRECT_CALLABLE_DECLARE(struct sk_buff *ipv6_gro_receive(struct list_head *,
+							   struct sk_buff *));
+INDIRECT_CALLABLE_DECLARE(int ipv6_gro_complete(struct sk_buff *, int));
+INDIRECT_CALLABLE_DECLARE(struct sk_buff *inet_gro_receive(struct list_head *,
+							   struct sk_buff *));
+INDIRECT_CALLABLE_DECLARE(int inet_gro_complete(struct sk_buff *, int));
+#endif /* _NET_IPV6_GRO_H */

net/core/dev.c

@@ -101,6 +101,7 @@
 #include <net/dsa.h>
 #include <net/dst.h>
 #include <net/dst_metadata.h>
+#include <net/gro.h>
 #include <net/pkt_sched.h>
 #include <net/pkt_cls.h>
 #include <net/checksum.h>
@@ -5751,8 +5752,6 @@ static void gro_normal_one(struct napi_struct *napi, struct sk_buff *skb)
 		gro_normal_list(napi);
 }
 
-INDIRECT_CALLABLE_DECLARE(int inet_gro_complete(struct sk_buff *, int));
-INDIRECT_CALLABLE_DECLARE(int ipv6_gro_complete(struct sk_buff *, int));
 static int napi_gro_complete(struct napi_struct *napi, struct sk_buff *skb)
 {
 	struct packet_offload *ptype;
@@ -5921,10 +5920,6 @@ static void gro_flush_oldest(struct napi_struct *napi, struct list_head *head)
 	napi_gro_complete(napi, oldest);
 }
 
-INDIRECT_CALLABLE_DECLARE(struct sk_buff *inet_gro_receive(struct list_head *,
-							   struct sk_buff *));
-INDIRECT_CALLABLE_DECLARE(struct sk_buff *ipv6_gro_receive(struct list_head *,
-							   struct sk_buff *));
 static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff *skb)
 {
 	u32 hash = skb_get_hash_raw(skb) & (GRO_HASH_BUCKETS - 1);

net/ipv6/ip6_offload.c

@@ -15,6 +15,7 @@
 #include <net/inet_common.h>
 #include <net/tcp.h>
 #include <net/udp.h>
+#include <net/gro.h>
 
 #include "ip6_offload.h"