Revert "Rename 586MC1 to GA-586IS"

This reverts commit 3390aa8d03.

src/machine/m_at_socket4.c

@@ -317,6 +317,7 @@ machine_at_586mc1_init(const machine_t *model)
 
     machine_at_award_common_init(model);
 
+    device_add(&sio_device);
     device_add(&intel_flash_bxt_device);
     device_add(&i430lx_device);