PNP / ACPI: Use ACPI_COMPANION_SET() during initialization

pnpacpi_add_device() calls acpi_bind_one() on an already registered
device, which is a mistake, but it can initialize the ACPI companion
field of the struct device to be registered using ACPI_COMPANION_SET()
instead, so make it do that.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>