PM: domains: fix domain_governor kernel-doc warnings

Fix kernel-doc warnings found when using "W=1".

domain_governor.c:54: warning: No description found for return value of 'default_suspend_ok'
domain_governor.c:266: warning: No description found for return value of '_default_power_down_ok'
domain_governor.c:412: warning: cannot understand function prototype: 'struct dev_power_governor pm_domain_always_on_gov = '

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Link: https://lore.kernel.org/r/20231205225856.32739-1-rdunlap@infradead.org


Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>