remove check_sig_hash

Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
diff --git a/library/ssl_srv.c b/library/ssl_srv.c
index f2f57b1..5cd9d71 100644
--- a/library/ssl_srv.c
+++ b/library/ssl_srv.c
@@ -1803,10 +1803,13 @@
      */
     if( sig_hash_alg_ext_present == 0 )
     {
-        mbedtls_md_type_t md_default = MBEDTLS_MD_SHA1;
-
-        if( mbedtls_ssl_check_sig_hash( ssl, md_default ) != 0 )
-            md_default = MBEDTLS_MD_NONE;
+        uint16_t sig_algs[] = { MBEDTLS_SSL_SIG_ALG(MBEDTLS_SSL_HASH_SHA1) };
+        mbedtls_md_type_t md_default = MBEDTLS_MD_NONE;
+        for( i = 0; i < sizeof(sig_algs)/sizeof(sig_algs[0]) ; i++ )
+        {
+            if( mbedtls_ssl_sig_alg_is_offered( ssl, sig_algs[ i ] ) )
+                md_default = MBEDTLS_MD_SHA1;
+        }
 
         mbedtls_ssl_sig_hash_set_const_hash( &ssl->handshake->hash_algs, md_default );
     }