PCI: pciehp: Clean up dmesg "Slot(%s)" messages

Print slot name consistently as "Slot(%s)".  I don't know whether that's
ideal, but we can at least do it the same way all the time.  No functional
change intended.

Tested-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>