x86: use year 2000 offset for cmos clock

We know it is already after 2000. Use the year 2000 offset for both 32
and 64 bit, which removes ifdefs and the 1970 magic.

[ tglx@linutronix.de: remove 1970 magic, replace bogus commit message ]

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/kernel/rtc.c

@@ -9,22 +9,18 @@
 #include <asm/vsyscall.h>
 
 #ifdef CONFIG_X86_32
-# define CMOS_YEARS_OFFS 1900
 /*
  * This is a special lock that is owned by the CPU and holds the index
  * register we are working with.  It is required for NMI access to the
  * CMOS/RTC registers.  See include/asm-i386/mc146818rtc.h for details.
  */
 volatile unsigned long cmos_lock = 0;
 EXPORT_SYMBOL(cmos_lock);
-#else
-/*
- * x86-64 systems only exists since 2002.
- * This will work up to Dec 31, 2100
- */
-# define CMOS_YEARS_OFFS 2000
 #endif
 
+/* For two digit years assume time is always after that */
+#define CMOS_YEARS_OFFS 2000
+
 DEFINE_SPINLOCK(rtc_lock);
 EXPORT_SYMBOL(rtc_lock);
 
@@ -136,11 +132,8 @@ unsigned long mach_get_cmos_time(void)
 		BCD_TO_BIN(century);
 		year += century * 100;
 		printk(KERN_INFO "Extended CMOS year: %d\n", century * 100);
-	} else {
+	} else
 		year += CMOS_YEARS_OFFS;
-		if (year < 1970)
-			year += 100;
-	}
 
 	return mktime(year, mon, day, hour, min, sec);
 }