elog: calculate year correctly in timestamp

This CL uses a 16-bit value (instead of an 8-bit value) for the year.
This is needed because the function internally does a "year % 100", so
the year should not be truncated to 8-bit before applying the modulo.

This fixes a regression introduced in commit e929a75.

BUG=b:200538760
TEST=deployed coreboot. Manually verified that year is correct using
     "elogtool list"
TEST=test_that -b $BOARD $DUT firmware_EventLog

Change-Id: I17578ff99af5b31b216ac53c22e53b1b70df5084
Signed-off-by: Ricardo Quesada <ricardoq@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/57816
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>

src/commonlib/bsd/elog.c

@@ -50,7 +50,7 @@ const void *event_get_data(const struct event_header *event)
 
 /* Populate timestamp in event header with given time. */
 void elog_fill_timestamp(struct event_header *event, uint8_t sec, uint8_t min,
-			 uint8_t hour, uint8_t mday, uint8_t mon, uint8_t year)
+			 uint8_t hour, uint8_t mday, uint8_t mon, uint16_t year)
 {
 	event->second = bin2bcd(sec);
 	event->minute = bin2bcd(min);