dual-image: Add reset-cs0-aspeed to reset the CS

When BMC is running on the secondary flash, and the primary flash is
updated, the BMC needs to reboot to the primary flash.

On aspeed, this is done

dual-image: Add reset-cs0-aspeed to reset the CS

When BMC is running on the secondary flash, and the primary flash is
updated, the BMC needs to reboot to the primary flash.

On aspeed, this is done by clearing the wdt2 state register bit, and
could be implemented by writing non-zero to
/sys/class/watchdog/watchdog1/access_cs0.
But it has a side effect that the CS will be swapped back to normal,
which means the running rootfs will be swapped to the primary flash.
So this needs to be done after the rootfs is umounted.

Add reset-cs0-aspeed to insert a line in `/run/initramfs/shutdown`
to write non-zero to /sys/class/watchdog/watchdog1/access_cs0.

Tested: Verify that the BMC is reboot to the primary flash after
flashing in the secondary image.

Signed-off-by: Lei YU <yulei.sh@bytedance.com>
Change-Id: I4c988017ed45131318625f349a84500e1831e171

show more ...