PCI: Remove pci_block_cfg_access() et al (unused)

PCI: Remove pci_block_cfg_access() et al (unused)

Remove the following unused functions from include/linux/pci.h:

  pci_block_cfg_access()
  pci_block_cfg_access_in_atomic()
  pci_unblock_cfg_access()

These were added by fb51ccbf217c ("PCI: Rework config space blocking
services"), though no callers were added.

Link: https://lore.kernel.org/r/20190715203416.37547-1-skunberg.kelsey@gmail.com
Signed-off-by: Kelsey Skunberg <skunberg.kelsey@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>