drm/msm/a6xx: Remove logically deadcode in a6xx_preempt.c

The ternary operator never returns -1 as `ring` will never be NULL.
Thus, the ternary operator is not needed.
Fix this by removing the ternary operation and only including the
value it will return when the `ring` is not NULL.

This was reported by Coverity Scan.
https://scan7.scan.coverity.com/#/project-view/51525/11354?selectedIssue=1600286

Fixes: 35d36dc ("drm/msm/a6xx: Add traces for preemption")
Signed-off-by: Everest K.C. <everestkc@everestkc.com.np>
Patchwork: https://patchwork.freedesktop.org/patch/619349/
Signed-off-by: Rob Clark <robdclark@chromium.org>

Author: everestkc

drivers/gpu/drm/msm/adreno/a6xx_preempt.c

@@ -297,8 +297,7 @@ void a6xx_preempt_trigger(struct msm_gpu *gpu)
 	 */
 	ring->restore_wptr = false;
 
-	trace_msm_gpu_preemption_trigger(a6xx_gpu->cur_ring->id,
-		ring ? ring->id : -1);
+	trace_msm_gpu_preemption_trigger(a6xx_gpu->cur_ring->id, ring->id);
 
 	spin_unlock_irqrestore(&ring->preempt_lock, flags);