rtc: Fix timestamp value for RTC_TIMESTAMP_BEGIN_1900

Printing "mktime64(1900, 1, 1, 0, 0, 0)" gives -2208988800.

Fixes: 83bbc5ac ("rtc: Add useful timestamp definitions")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

include/linux/rtc.h

@@ -162,7 +162,7 @@ struct rtc_device {
 #define to_rtc_device(d) container_of(d, struct rtc_device, dev)
 
 /* useful timestamps */
-#define RTC_TIMESTAMP_BEGIN_1900	-2208989361LL /* 1900-01-01 00:00:00 */
+#define RTC_TIMESTAMP_BEGIN_1900	-2208988800LL /* 1900-01-01 00:00:00 */
 #define RTC_TIMESTAMP_BEGIN_2000	946684800LL /* 2000-01-01 00:00:00 */
 #define RTC_TIMESTAMP_END_2063		2966371199LL /* 2063-12-31 23:59:59 */
 #define RTC_TIMESTAMP_END_2099		4102444799LL /* 2099-12-31 23:59:59 */