[PATCH] DPP: Fix compiler warning of testing code

[Masashi Honma]

../src/common/dpp.c: In function 'dpp_test_gen_invalid_key':
../src/common/dpp.c:5531:10: warning: return makes integer from pointer without a cast [-Wint-conversion]
   return NULL;
          ^

Signed-off-by: Masashi Honma <masashi.honma at gmail.com>
---
 src/common/dpp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/common/dpp.c b/src/common/dpp.c
index 12a154b..a6ffa9d 100644
--- a/src/common/dpp.c
+++ b/src/common/dpp.c
@@ -5528,7 +5528,7 @@ static int dpp_test_gen_invalid_key(struct wpabuf *msg,
 
 	group = EC_GROUP_new_by_curve_name(OBJ_txt2nid(curve->name));
 	if (!group)
-		return NULL;
+		return -1;
 
 	ctx = BN_CTX_new();
 	point = EC_POINT_new(group);
-- 
2.7.4