pci/pcie: rename hotplug handler callbacks

pci/pcie: rename hotplug handler callbacks

The callbacks are also called for cold plugged devices. Drop the "hot"
to better match the actual callback names.

While at it, also rename  pcie_cap_slot_hotplug_common() to
pcie_cap_slot_plug_common().

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>