PCI: do not call pci_set_power_state with PCI_D3cold

PCI subsystem has not been ready for D3cold support yet.  So
PCI_D3cold should not be used as parameter for pci_set_power_state.
This patch is needed for upcoming PCI_D3cold support.

This patch has no functionality change, because pci_set_power_state
will bound the parameter to PCI_D3hot too.

CC: Michal Miroslaw <mirq-linux@rere.qmqm.pl>
CC: Jesse Barnes <jesse.barnes@intel.com>
Reviewed-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Huang Ying <ying.huang@intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>