PCI: Tidy config space save/restore messages

Update config space save/restore debug messages so they line up better.
Previously:

  nvme 0000:05:00.0: saving config space at offset 0x4 (reading 0x20100006)
  nvme 0000:05:00.0: saving config space at offset 0x8 (reading 0x1080200)
  nvme 0000:05:00.0: saving config space at offset 0xc (reading 0x0)

  nvme 0000:05:00.0: restoring config space at offset 0x4 (was 0x0, writing 0x20100006)

Now:

  nvme 0000:05:00.0: save config 0x04: 0x20100006
  nvme 0000:05:00.0: save config 0x08: 0x01080200
  nvme 0000:05:00.0: save config 0x0c: 0x00000000

  nvme 0000:05:00.0: restore config 0x04: 0x00000000 -> 0x20100006

No functional change intended.  Enable these messages by setting
CONFIG_DYNAMIC_DEBUG=y and adding 'dyndbg="file drivers/pci/* +p"'
to kernel parameters.

Link: https://lore.kernel.org/r/20230823191831.476579-1-helgaas@kernel.org


Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Rafael J. Wysocki <rafael@kernel.org>