Made the Pravetz use the AT keyboard.

src/machine/m_xt.c

@@ -339,7 +339,10 @@ machine_xt_pravetz16_imko4_init(const machine_t *model)
     if (bios_only || !ret)
 	    return ret;
 
-    machine_xt_init_ex(model);
+    device_add(&keyboard_at_device);
+
+    machine_xt_common_init(model);
+
     return ret;
 }