net: fix build error in devmap helper calls

Initial patches missed case with CONFIG_BPF_SYSCALL not set.

Fixes: 11393cc9 ("xdp: Add batching support to redirect map")
Fixes: 97f91a7c ("bpf: add bpf_redirect_map helper routine")
Signed-off-by: NJohn Fastabend <john.fastabend@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/linux/bpf.h

@@ -318,6 +318,12 @@ static inline void bpf_long_memcpy(void *dst, const void *src, u32 size)
 
 /* verify correctness of eBPF program */
 int bpf_check(struct bpf_prog **fp, union bpf_attr *attr);
+
+/* Map specifics */
+struct net_device  *__dev_map_lookup_elem(struct bpf_map *map, u32 key);
+void __dev_map_insert_ctx(struct bpf_map *map, u32 index);
+void __dev_map_flush(struct bpf_map *map);
+
 #else
 static inline struct bpf_prog *bpf_prog_get(u32 ufd)
 {
@@ -356,6 +362,20 @@ static inline int __bpf_prog_charge(struct user_struct *user, u32 pages)
 static inline void __bpf_prog_uncharge(struct user_struct *user, u32 pages)
 {
 }
+
+static inline struct net_device  *__dev_map_lookup_elem(struct bpf_map *map,
+						       u32 key)
+{
+	return NULL;
+}
+
+static inline void __dev_map_insert_ctx(struct bpf_map *map, u32 index)
+{
+}
+
+static inline void __dev_map_flush(struct bpf_map *map)
+{
+}
 #endif /* CONFIG_BPF_SYSCALL */
 
 /* verifier prototypes for helper functions called from eBPF programs */
@@ -379,9 +399,4 @@ extern const struct bpf_func_proto bpf_get_stackid_proto;
 void bpf_user_rnd_init_once(void);
 u64 bpf_user_rnd_u32(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
 
-/* Map specifics */
-struct net_device  *__dev_map_lookup_elem(struct bpf_map *map, u32 key);
-void __dev_map_insert_ctx(struct bpf_map *map, u32 index);
-void __dev_map_flush(struct bpf_map *map);
-
 #endif /* _LINUX_BPF_H */