Fix compilation errors when building sign_with_k test function

Signed-off-by: Andrzej Kurek <andrzej.kurek@arm.com>
diff --git a/include/tinycrypt/ecc_dsa.h b/include/tinycrypt/ecc_dsa.h
index 0001ecb..30cbe5e 100644
--- a/include/tinycrypt/ecc_dsa.h
+++ b/include/tinycrypt/ecc_dsa.h
@@ -115,7 +115,7 @@
  * Refer to uECC_sign() function for real applications.
  */
 int uECC_sign_with_k(const uint8_t *private_key, const uint8_t *message_hash,
-		     unsigned int hash_size, uECC_word_t *k, uint8_t *signature)
+		     unsigned int hash_size, uECC_word_t *k, uint8_t *signature);
 #endif
 
 /**