drm/panthor: Don't try to enable extract events

drm/panthor: Don't try to enable extract events

Not only this only works once, because of how extract events work
(event is enabled if the req and ack bit differ, and it's signalled
by the FW by setting identical req and ack, to re-enable the event,
we need to toggle the bit, which we never do). But more importantly,
we never do anything with this event, so we're better off dropping it
when programming the CS slot.

v2:
- Add R-b

v3:
- Collect R-b

Reviewed-by: Steven Price <steven.price@arm.com>
Reviewed-by: Chia-I Wu <olvaffe@gmail.com>
Link: https://patch.msgid.link/20251128094839.3856402-3-boris.brezillon@collabora.com
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>