Convert existing drm_exec transactions, like GT pagefault validation,
non-LR exec() IOCTL and the rebind worker to support
exhaustive eviction using the xe_validation_guard().
v2:
- Adapt to signature change in xe_validation_guard() (Matt Brost)
- Avoid gotos from within xe_validation_guard() (Matt Brost)
- Check error return from xe_validation_guard()