PCI: Clean up accessor macro formatting

PCI: Clean up accessor macro formatting

Clean up formatting of PCI accessor macros:

  - Put return statements on own line

  - Add a few empty lines for better readability

  - Align macro continuation backslashes

  - Correct function call argument indentation level

  - Reorder variable declarations to order of use

  - Drop unnecessary variable initialization

Link: https://lore.kernel.org/r/20240429094707.2529-2-ilpo.jarvinen@linux.intel.com
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
[bhelgaas: drop initialization, tweak variables to order of use]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>