microblaze/PCI: Remove Null PCI config access unused functions

Remove unused NULL_PCI_OP config access functions, for the case when
we can't find a hose.

Remove unused EARLY_PCI_OP and other declarations.

Signed-off-by: Thippeswamy Havalige <thippeswamy.havalige@amd.com>
Link: https://lore.kernel.org/r/20221025065214.4663-3-thippeswamy.havalige@amd.com


Signed-off-by: Michal Simek <michal.simek@amd.com>