Revert "drm/xe: Skip exec queue schedule toggle if queue is idle during suspend"

In the Linux kernel, the following vulnerability has been resolved:

Revert "drm/xe: Skip exec queue schedule toggle if queue is idle during suspend"

This reverts commit 8533051ce92015e9cc6f75e0d52119b9d91610b6.

The idle-skip optimization bypasses GuC suspend, so the GPU may not

perform the context switch that flushes TLB entries for invalidated

userptr VMAs. In LR/preempt-fence VM mode, this can lead to missed TLB

invalidation and page faults during userptr invalidation tests.

Restore unconditional schedule toggling on suspend so the context-switch

TLB flush is always performed.

This optimization will be reintroduced with a fix that does not skip

suspend in LR/preempt-fence VM mode.

(cherry picked from commit 6a1e7934d9a6cf46aecae00a99c2603d1295e170)