hrtimers: Merge __hrtimer_init() into __hrtimer_setup()

__hrtimer_init() is only called by __hrtimer_setup(). Simplify by merging
__hrtimer_init() into __hrtimer_setup().

Signed-off-by: Nam Cao <namcao@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/all/8a0a847a35f711f66b2d05b57255aa44e7e61279.1738746927.git.namcao@linutronix.de