Revert "ACPI / LPSS: introduce a 'proxy' device to power on LPSS for DMA"

Revert commit 6c17ee44 (ACPI / LPSS: introduce a 'proxy' device
to power on LPSS for DMA), as it introduced registration and probe
ordering problems between devices on the LPSS that may lead to full
hard system hang on boot in some cases.