acpi_lid: Remove duplicate events

Remove extra acpi_UserNotify() call per event. Filter duplicate
notifications received from ACPI without actual status change.

Without this on my Dell XPS 13 9310 I saw 4 devd events for either
open or close, now only one.

MFC after: 1 month

(cherry picked from commit 1a3ee6002f3e008e0bc29d04c976285434503e19)