PCI: Fix missing inline for pci_pr3_present()

The inline prefix was missing in the dummy function pci_pr3_present()
definition.  Fix it.

Reported-by: kbuild test robot <lkp@intel.com>
Fixes: 52525b7a ("PCI: Add a helper to check Power Resource Requirements _PR3 existence")
Link: https://lore.kernel.org/r/201910212111.qHm6OcWx%lkp@intel.com


Signed-off-by: Takashi Iwai <tiwai@suse.de>