chip/stm32/clock: Don't wake up the host when the host resets rtc
chip/stm32/clock: Don't wake up the host when the host resets rtc

The way AP resets ec rtc alarm is to set rtc alarm wake time in 0 sec.
In current implementation, this still sets host_rtc_alarm_set.
...So when rtc irq is triggered next time, it wakes up the host even if
the alarm is not set by the host.
Let's fix it.

BUG=b:66971951, b:67379662
BRANCH=none
TEST='powerd_dbus_suspend' and see the host stay in suspend mode

Change-Id: I1e14f669e3d887874548813c7c5b4d21d80bc62e
Signed-off-by: Philip Chen <3ee404f9ef892bc3fda6e6a76e65843b5fa44db2@google.com>
Reviewed-on: https://chromium-review.googlesource.com/699657
Commit-Ready: Philip Chen <3ee404f9ef892bc3fda6e6a76e65843b5fa44db2@chromium.org>
Tested-by: Philip Chen <3ee404f9ef892bc3fda6e6a76e65843b5fa44db2@chromium.org>
Reviewed-by: Shawn N <5259333ce42e3ace6a73988cec7115ed9d3a661a@chromium.org>

coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec