Fixes following error uncovered while building ath79/tiny on 5.4:

 Package kmod-hwmon-sch5627 is missing dependencies for the following
 libraries:
 watchdog.ko

See the similar commit e546e625 ("malta: fix missing watchdog core
dependency for hwmon-sch5627") for a detailed explanation.

Signed-off-by: David Bauer <mail@david-bauer.net>