drm/xe/exec_queue: Remove duplicated code

This code section is the same as the body of
xe_exec_queue_last_fence_put_unlocked() so call the function instead and
remove duplicated code to make maintenance easier.

Signed-off-by: Francois Dugast <[e-mail]>
Reviewed-by: Matthew Brost <[e-mail]>
Signed-off-by: Matthew Brost <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/xe/xe_exec_queue.c

···
 {
 	xe_exec_queue_last_fence_lockdep_assert(q, vm);
 
-	if (q->last_fence) {
-		dma_fence_put(q->last_fence);
-		q->last_fence = NULL;
-	}
+	xe_exec_queue_last_fence_put_unlocked(q);
 }
 
 /**