PCI: pciehp: Announce slot capabilities (slot #, button, LEDs, etc)

We already have the vendor/device IDs from pci_setup_device(), so drop that
info and print things that will be more useful for debugging: the slot
number and presence of button/indicators/link active reporting/etc.

No functional change.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>