Rename ssl_set_bio_timeout() to set_bio()

Initially thought it was best to keep the old function around and add a new
one, but this so many ssl_set_xxx() functions are changing anyway...
diff --git a/programs/ssl/ssl_server2.c b/programs/ssl/ssl_server2.c
index 87b4a2e..7b85ce8 100644
--- a/programs/ssl/ssl_server2.c
+++ b/programs/ssl/ssl_server2.c
@@ -1819,9 +1819,9 @@
     }
 
     if( opt.nbio == 2 )
-        mbedtls_ssl_set_bio_timeout( &ssl, &client_fd, my_send, my_recv, NULL );
+        mbedtls_ssl_set_bio( &ssl, &client_fd, my_send, my_recv, NULL );
     else
-        mbedtls_ssl_set_bio_timeout( &ssl, &client_fd, mbedtls_net_send, mbedtls_net_recv,
+        mbedtls_ssl_set_bio( &ssl, &client_fd, mbedtls_net_send, mbedtls_net_recv,
 #if defined(MBEDTLS_HAVE_TIME)
                              opt.nbio == 0 ? mbedtls_net_recv_timeout : NULL
 #else