Unify parsing of the signature algorithms extension

Signed-off-by: Gabor Mezei <gabor.mezei@arm.com>
diff --git a/library/ssl_tls13_client.c b/library/ssl_tls13_client.c
index 320c5b4..69934bd 100644
--- a/library/ssl_tls13_client.c
+++ b/library/ssl_tls13_client.c
@@ -1612,7 +1612,7 @@
             case MBEDTLS_TLS_EXT_SIG_ALG:
                 MBEDTLS_SSL_DEBUG_MSG( 3,
                         ( "found signature algorithms extension" ) );
-                ret = mbedtls_ssl_tls13_parse_sig_alg_ext( ssl, p,
+                ret = mbedtls_ssl_parse_sig_alg_ext( ssl, p,
                               p + extension_data_len );
                 if( ret != 0 )
                     return( ret );