sched/idle: Switch to use hrtimer_setup_on_stack()

hrtimer_setup_on_stack() takes the callback function pointer as argument
and initializes the timer completely.

Replace hrtimer_init_on_stack() and the open coded initialization of
hrtimer::function with the new setup mechanism.

The conversion was done with Coccinelle.

Signed-off-by: Nam Cao <namcao@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/17f9421fed6061df4ad26a4cc91873d2c078cb0f.1730386209.git.namcao@linutronix.de