PCI/ACPI: Use DEVICE_ACPI_HANDLE rather than searching acpi_pci_roots

When we bind a device to an ACPI handle, the handle is stored in
dev->archdata.acpi_handle.  For such devices, there's no need to
search the acpi_pci_roots list with acpi_get_pci_rootbridge_handle();
we can just use DEVICE_ACPI_HANDLE(dev) directly.

[bhelgaas: changelog, reorder "if" to avoid negation]
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Len Brown <lenb@kernel.org>
Cc: linux-acpi@vger.kernel.org