Previously several things used by portdrv_core.c and portdrv_pci.c were
shared by defining them in portdrv.h.  Now that portdrv_core.c and
portdrv_pci.c have been squashed, move things that can be private into
portdrv.c.  No functional change intended.

Link: https://lore.kernel.org/r/20221019204127.44463-3-helgaas@kernel.orgSigned-off-by: NBjorn Helgaas <bhelgaas@google.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NKeith Busch <kbusch@kernel.org>