x86: don't panic when RTC returns invalid values

kernel/src/arch/x86/peripherals/rtc.rs

@@ -179,15 +179,15 @@ impl Rtc {
 impl DateTime {
     pub fn to_seconds(self) -> u64 {
         let date = chrono::NaiveDate::from_ymd_opt(
-            2000 + self.year as i32,
-            self.month as u32,
-            self.day_of_month as u32,
+            2000 + self.year.max(100) as i32,
+            self.month.clamp(1, 12) as u32,
+            self.day_of_month.clamp(1, 31) as u32,
         )
         .unwrap();
         let time = chrono::NaiveTime::from_hms_opt(
-            self.hours as u32,
-            self.minutes as u32,
-            self.seconds as u32,
+            self.hours.clamp(0, 23) as u32,
+            self.minutes.clamp(0, 59) as u32,
+            self.seconds.clamp(0, 59) as u32,
         )
         .unwrap();