PCI PM: Rearrange code in pci-driver.c

Rename two functions and rearrange code in drivers/pci/pci-driver.c
so that it's easier to follow.  In particular, separate invocations
of the legacy callbacks from the rest of the new callbacks' code.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>