ACPI: processor: idle: Remove redundant static variable and rename cstate check function

ACPI: processor: idle: Remove redundant static variable and rename cstate check function

The function acpi_processor_cstate_first_run_checks() is currently called
only once during initialization in acpi_processor_register_idle_driver().

Since its execution is already limited by the caller's lifecycle, the
internal static 'first_run' variable is redundant and can be safely
removed.

Additionally, the current function name is no longer descriptive of its
behavior, so rename the function to acpi_processor_update_max_cstate()
to better reflect its actual purpose.

Signed-off-by: Huisong Li <lihuisong@huawei.com>
Link: https://patch.msgid.link/20260311065038.4151558-4-lihuisong@huawei.com
[ rjw: Changelog edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>