ACPI: dock: Remove redundant ACPI NS walk

Combined two ACPI namespace walks, which look for dock stations
and then bays separately, into a single walk.

Signed-off-by: Toshi Kani <toshi.kani@hp.com>
Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>