microblaze/PCI: Remove unused early_read_config_byte() et al declarations

early_read_config_byte() and similar are declared but never defined.

Remove the unused declarations.

Signed-off-by: Thippeswamy Havalige <thippeswamy.havalige@amd.com>
Link: https://lore.kernel.org/r/20221025065214.4663-2-thippeswamy.havalige@amd.com


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