bpf: testing: fix devmap tests

Apparently through one of my revisions of the initial patches
series I lost the devmap test. We can add more testing later but
for now lets fix the simple one we have.

Fixes: 546ac1ffb7 "bpf: add devmap, a map for storing net device references"
Reported-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

tools/testing/selftests/bpf/test_maps.c

@@ -440,7 +440,7 @@ static void test_arraymap_percpu_many_keys(void)
 
 static void test_devmap(int task, void *data)
 {
-	int next_key, fd;
+	int fd;
 	__u32 key, value;
 
 	fd = bpf_create_map(BPF_MAP_TYPE_DEVMAP, sizeof(key), sizeof(value),
@@ -620,6 +620,8 @@ static void run_all_tests(void)
 
 	test_arraymap_percpu_many_keys();
 
+	test_devmap(0, NULL);
+
 	test_map_large();
 	test_map_parallel();
 	test_map_stress();