Medium [CVE-2026-72008] Fix possible nullptr KP in HWV cleanup/on-check

In the Linux kernel, the following vulnerability has been resolved: pmdomain: mediatek: Fix possible nullptr KP in HWV cleanup/on-check Should probe fail for HW_VOTER type power domains, this driver was unconditionally trying to perform cleanup for DIRECT_CTL domains, but only after checking if the target domain is powered on... with the DIRECT_CTL scpsys_domain_is_on() code again.

And there's more: the scpsys_domain_is_on() function is also being unconditionally used in the probe path, for any power domain that has flag MTK_SCPD_KEEP_DEFAULT_OFF! This bug was never experienced by anyone because the HWV domains never failed probe, and because none of those is declared with the aforementioned flag - but it's still something critical.

In order to fix this, add a check for MTCMOS Type and, based on that, call the correct functions for an "is on" check, and also do the same for the cleanup path, calling the correct functions for the "power off" action.

For the latter, since there's a call to pm_genpd_remove() right before calling power_off, be cautious and add a variation of the power off functions (with a _internal suffix) for those to get a pointer to scpsys_domain instead of one to generic_pm_domain as, even if that's still working, this is way too much fragile and would break at some point.