intel/skylake: ensure the RTC time is set

In 2014 or so the RTC code was changed to assume the ALTCENTRY
register (0x32) as always being utilized for creating an rtc_time.
However, one needs to ensure it's set at least once otherwise
the year field in rtc_time is not sane.

In practice this doesn't matter unless somone wants to use the
full year value. cmos_init() should do the same thing in the
rtc fail case, but the machine I had never had that set correctly.

BUG=chrome-os-partner:47388
BRANCH=None
TEST=Booted glados w/ 0xff ALTCENTRY value. New value is 0x20.

Change-Id: I028f801c5d717a0018ed00df82c25b466d64670c
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: 7d5be5bc697bef60a264ddc7f67755aa96088d36
Original-Change-Id: I6e12a30c9e08d8c1002e4cef0f143f0f88009e92
Original-Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/311264
Original-Reviewed-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: http://review.coreboot.org/12411
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

src/soc/intel/skylake/pmc.c

@@ -139,6 +139,9 @@ static void pch_rtc_init(void)
 		printk(BIOS_DEBUG, "rtc_failed = 0x%x\n", rtc_failed);
 	}
 
+	/* Ensure the date is set including century byte. */
+	cmos_check_update_date();
+
 #if IS_ENABLED(CONFIG_CHROMEOS_VBNV_CMOS)
 	pch_cmos_init_preserve(rtc_failed);
 #else