Replace acpi_bus_get_device() that is going to be dropped with
acpi_fetch_acpi_dev().

No intentional functional impact.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/10025610.nUPlyArG6x@kreacherSigned-off-by: Will Deacon <will@kernel.org>