Increase the Hamming distance of uECC_generate_random_int returns

Signed-off-by: Andrzej Kurek <andrzej.kurek@arm.com>
diff --git a/tinycrypt/ecc_dsa.c b/tinycrypt/ecc_dsa.c
index 70f9c8b..bb3ed81 100644
--- a/tinycrypt/ecc_dsa.c
+++ b/tinycrypt/ecc_dsa.c
@@ -109,7 +109,7 @@
 		uECC_vli_clear(tmp);
 		tmp[0] = 1;
 	}
-	else if (!uECC_generate_random_int(tmp, curve_n, num_n_words)) {
+	else if (uECC_generate_random_int(tmp, curve_n, num_n_words) != UECC_SUCCESS) {
 		return UECC_FAILURE;
 	}