PCI/ACPI: Remove the need for 'struct hotplug_params'

We used to first parse all the _HPP and _HPX tables before using the
information to program registers of PCIe devices.  Up through HPX Type 2,
there was only one structure of each type, so we could cheat and store it
on the stack.

With HPX Type 3 we get an arbitrary number of entries, so the above model
doesn't scale that well.  Instead of parsing all tables at once, parse and
program each entry separately.  For _HPP and _HPX Types 0 through 2, this
is functionally equivalent.  The change enables the upcoming _HPX Type 3 to
integrate more easily.

Link: https://lore.kernel.org/lkml/20190208162414.3996-3-mr.nuke.me@gmail.com


Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
[bhelgaas: fix build errors]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>