zephyr: npcx: Change RTC IRQ enable/disable mechanism
zephyr: npcx: Change RTC IRQ enable/disable mechanism

This CL enables the RTC's irq when users set rtc alarm and disables it
when users reset rtc alarm. It makes sure rtc alarm works properly
when someone turn off the related WKEN unexpectedly.

BUG=b:183745774
BRANCH=none
TEST=zmake testall

Signed-off-by: Mulin Chao <6bbc5af053a1dfdc363be6857f30de4ac3bcbd16@nuvoton.com>
Change-Id: I1da24a497f10e2b1b94546979659e1eb188b1028
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2821115
Tested-by: Wealian Liao <b980917544b235741b592c0c8e1e53fb264e55ff@nuvoton.corp-partner.google.com>
Reviewed-by: Jack Rosenthal <d3f605bef1867f59845d4ce6e4f83b8dc9e4e0ae@chromium.org>
Reviewed-by: Wai-Hong Tam <04b587fdf5845741a0c5a8b9cd59ca72d73ef8fc@google.com>
Reviewed-by: Simon Glass <c00b0378376498bd9cd974c388df8854c0131d27@chromium.org>
Reviewed-by: Keith Short <f6d578f97033c25f1206cb57d52f358974c82954@chromium.org>
Commit-Queue: Jack Rosenthal <d3f605bef1867f59845d4ce6e4f83b8dc9e4e0ae@chromium.org>

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