microblaze/PCI: Remove unused allocation & free of PCI host bridge structure

Remove unused allocation and freeing of PCI host bridge structure.

Signed-off-by: Thippeswamy Havalige <thippeswamy.havalige@amd.com>
Link: https://lore.kernel.org/r/20221025065214.4663-7-thippeswamy.havalige@amd.com


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