hrtimer: Improve kernel message printing

  - Join split message for easier grepping,
  - Use pr_*() instead of printk*(),
  - Use %u to format unsigned cpu numbers.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20180712144118.8819-1-geert+renesas@glider.be