add default options to fbcon section in MiniGUI.cfg

etc/MiniGUI.cfg

@@ -153,6 +153,16 @@ dpi=96
 # Note that under compositing schema, double buffering is always enabled.
 # Since 5.0.10.
 double_buffering=true
+
+# Whether the async. update is enabled.
+# Use `true` or `yes` for enabled, anything else for disabled.
+# Since 5.0.13.
+async_update=yes
+
+# The update interval for the asyn. updater (milli-seconds).
+# This setting is only valid when drmWaitVBlank doesn't work correctly.
+# Since 5.0.13.
+update_interval=15
 #}}
 
 #{{ifdef _MGGAL_PCXVFB