cpufreq/amd-pstate: Enable ITMT support after initializing core rankings

cpufreq/amd-pstate: Enable ITMT support after initializing core rankings

When working on dynamic ITMT priority support, it was observed that
"asym_prefer_cpu" on AMD systems supporting Preferred Core ranking
was always set to the first CPU in the sched group when the system boots
up despite another CPU in the group having a higher ITMT ranking.

"asym_prefer_cpu" is cached when the sched domain hierarchy is
constructed. On AMD systems that support Preferred Core rankings, sched
domains are rebuilt when ITMT support is enabled for the first time from
amd_pstate*_cpu_init().

Since amd_pstate*_cpu_init() is called to initialize the cpudata for
each CPU, the ITMT support is enabled after the first CPU initializes
its asym priority but this is too early since other CPUs have not yet
initialized their asym priorities and the sched domain is rebuilt only
once when the support is toggled on for the first time.

Initialize the asym priorities first in amd_pstate*_cpu_init() and then
enable ITMT support later in amd_pstate_register_driver() to ensure all
CPUs have correctly initialized their asym priorities before sched
domain hierarchy is rebuilt.

Clear the ITMT support when the amd-pstate driver unregisters since core
rankings cannot be trusted unless the update_limits() callback is
operational.

Remove the delayed work mechanism now that ITMT support is only toggled
from the driver init path which is outside the cpuhp critical section.

Fixes: f3a052391822 ("cpufreq: amd-pstate: Enable amd-pstate preferred core support")
Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Link: https://lore.kernel.org/r/20250411081439.27652-1-kprateek.nayak@amd.com
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>