Remove dependency of ssl_cookie on SHA-224
Cookies are fully opaque so we can change the hash used at any time, it's not
part of the API.
The cookie module handles truncation, so it's simpler to always use SHA-256
rather than check if SHA-224 is available.
diff --git a/library/ssl_cookie.c b/library/ssl_cookie.c
index 56e9bdd..6f0be8a 100644
--- a/library/ssl_cookie.c
+++ b/library/ssl_cookie.c
@@ -50,7 +50,7 @@
* with max 32 bytes of cookie for DTLS 1.0
*/
#if defined(MBEDTLS_SHA256_C)
-#define COOKIE_MD MBEDTLS_MD_SHA224
+#define COOKIE_MD MBEDTLS_MD_SHA256
#define COOKIE_MD_OUTLEN 32
#define COOKIE_HMAC_LEN 28
#elif defined(MBEDTLS_SHA512_C)