PCI: Add a generic weak pcibios_align_resource()

Multiple architectures define this as a trivial function, and I'm adding
another one as part of the RISC-V port.  Add a __weak version of
pcibios_align_resource() and delete the now-obselete ones in a handful of
ports.

The only functional change should be that a handful of ports used to export
pcibios_fixup_bus().  Only some architectures export this, so I just
dropped it.

Signed-off-by: Palmer Dabbelt <palmer@dabbelt.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>