drm/panthor: Be robust against runtime PM resume failures in the suspend path

drm/panthor: Be robust against runtime PM resume failures in the suspend path

The runtime PM resume operation is not guaranteed to succeed, but if it
fails, the device should be in a suspended state. Make sure we're robust
to resume failures in the unplug path.

v3:
- Fix typo
- Add R-bs

v2:
- Move the bit that belonged in the next commit
- Drop the panthor_device_unplug() changes

Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Adrian Larumbe <adrian.larumbe@collabora.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241211075419.2333731-3-boris.brezillon@collabora.com