watchdog: export watchdog_get_ticks_until_next_expiration function
watchdog: export watchdog_get_ticks_until_next_expiration function

This function returns the number of ticks until the next watchdog that will
expire. This function main purpose is to support a tickless kernel.

Signed-off-by: Fabien Parent <2a93cde040adee823a667eed2882d05f12a84573@gmail.com>

mtitinger/phabos,mtitinger/phabos