rtc.c: do not print argument of ioctls that have no arguments

* rtc.c (rtc_ioctl): Do not print argument of RTC_{A,U,P,W}IE_{ON,OFF}
and RTC_VL_CLR ioctls.
diff --git a/rtc.c b/rtc.c
index c54b9a8..bf88929 100644
--- a/rtc.c
+++ b/rtc.c
@@ -126,6 +126,19 @@
 		printnum_int(tcp, arg, "%d");
 		break;
 #endif
+	case RTC_AIE_ON:
+	case RTC_AIE_OFF:
+	case RTC_UIE_ON:
+	case RTC_UIE_OFF:
+	case RTC_PIE_ON:
+	case RTC_PIE_OFF:
+	case RTC_WIE_ON:
+	case RTC_WIE_OFF:
+#ifdef RTC_VL_CLR
+	case RTC_VL_CLR:
+#endif
+		/* no args */
+		break;
 	default:
 		return RVAL_DECODED;
 	}