pmdomain: core: Add residency reflection for domain-idlestates to debugfs

For regular cpuidle states we are reflecting over the selected/entered
state to see if the sleep-duration meets the residency for the state. The
output from the reflection is an "above" value to indicate the number of
times the state was too deep and a "below" value for the number of times it
was too shallow.

Let's implement the similar thing for genpd's domain-idlestates along with
genpd's governor and put the information in the genpd's debugfs.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Link: https://lore.kernel.org/r/20250314100103.1294715-5-ulf.hansson@linaro.org