microblaze: resource/PCI: align functions now return start of resource

This change should be part of b26b2d49

Origin description:

resource/PCI: align functions now return start of resource

As suggested by Linus, align functions should return the start
of a resource, not void. An update of "res->start" is no longer
necessary.

Signed-off-by: Michal Simek <monstr@monstr.eu>