PM: sleep: Take advantage of %ps to simplify debug output

initcall_debug previous and new output:

...PM: calling pci_pm_suspend+0x0/0x1b0 @ 3233, parent: pci0000:00

...PM: calling pci_pm_suspend @ 3233, parent: pci0000:00

Signed-off-by: Len Brown <len.brown@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>