ACPI: processor: idle: Drop unnecessary (void *) conversion

The (void *) type pointer does not need to be cast, so don't do
that in lapic_timer_check_state().

Signed-off-by: Zhou jie <zhoujie@nfschina.com>
[ rjw: Subject and changelog edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>