drm/panthor: Fix immediate ticking on a disabled tick

drm/panthor: Fix immediate ticking on a disabled tick

We have a few paths where we schedule the tick work immediately without
changing the resched_target. If the tick was stopped, this would lead
to a remaining_jiffies that's always > 0, and it wouldn't force a full
tick in that case. Add extra checks to cover that case properly.

v2:
- Fix typo
- Simplify the code as suggested by Steve

v3:
- Collect R-b

Fixes: de8548813824 ("drm/panthor: Add the scheduler logical block")
Reviewed-by: Steven Price <steven.price@arm.com>
Reviewed-by: Chia-I Wu <olvaffe@gmail.com>
Link: https://patch.msgid.link/20251128094839.3856402-6-boris.brezillon@collabora.com
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>