Add RTC peripheral from ASF4 (CALENDAR)

Change-Id: I04b6608b72f22cf9829a5bfdddf7cbbbbe8ebb3e
diff --git a/sysmoOCTSIM/main.c b/sysmoOCTSIM/main.c
index 5fac323..091cd0b 100644
--- a/sysmoOCTSIM/main.c
+++ b/sysmoOCTSIM/main.c
@@ -94,6 +94,7 @@
 
 	cache_init();
 	cache_enable(CMCC);
+	calendar_enable(&CALENDAR_0);
 
 	/* increase drive strength of 20Mhz SIM clock output to 8mA
 	 * (there are 8 inputs + traces to drive!) */