ACPI / ia64 / sba_iommu: Restore the working initialization ordering

Commit 66345d5f (ACPI / ia64 / sba_iommu: Use ACPI scan handler
for device discovery) changed the ordering of SBA (System Bus Adapter)
IOMMU initialization with respect to the PCI host bridge initialization
which broke things inadvertently, because the SBA IOMMU initialization
code has to run after the PCI host bridge has been initialized.

Fix that by reworking the SBA IOMMU ACPI scan handler so that it
claims the discovered matching ACPI device objects without attempting
to initialize anything and move the entire SBA IOMMU initialization
to sba_init() that runs after the PCI bus has been enumerated.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=76691


Fixes: 66345d5f (ACPI / ia64 / sba_iommu: Use ACPI scan handler for device discovery)
Reported-and-tested-by: Émeric Maschino <emeric.maschino@gmail.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: 3.11+ <stable@vger.kernel.org> # 3.11+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>