Make use of MBEDTLS_MAX_HASH_SIZE macro

Signed-off-by: Przemek Stekiel <przemyslaw.stekiel@mobica.com>
diff --git a/library/ssl_tls12_client.c b/library/ssl_tls12_client.c
index f814094..d1ec55c 100644
--- a/library/ssl_tls12_client.c
+++ b/library/ssl_tls12_client.c
@@ -2330,11 +2330,8 @@
     if( mbedtls_ssl_ciphersuite_uses_server_signature( ciphersuite_info ) )
     {
         size_t sig_len, hashlen;
-#if defined(MBEDTLS_USE_PSA_CRYPTO)
-        unsigned char hash[PSA_HASH_MAX_SIZE];
-#else
-        unsigned char hash[MBEDTLS_MD_MAX_SIZE];
-#endif
+        unsigned char hash[MBEDTLS_HASH_MAX_SIZE];
+
         mbedtls_md_type_t md_alg = MBEDTLS_MD_NONE;
         mbedtls_pk_type_t pk_alg = MBEDTLS_PK_NONE;
         unsigned char *params = ssl->in_msg + mbedtls_ssl_hs_hdr_len( ssl );