drm/amdkfd: validate pdd where it acquired first

Currently pdd is validate after dereferencing it, which is
not correct, Thus validate pdd before its first use.
Signed-off-by: NManinder Singh <maninder1.s@samsung.com>
Signed-off-by: NOded Gabbay <oded.gabbay@gmail.com>

drivers/gpu/drm/amd/amdkfd/kfd_process.c

@@ -420,6 +420,12 @@ void kfd_unbind_process_from_device(struct kfd_dev *dev, unsigned int pasid)
 	pqm_uninit(&p->pqm);
 
 	pdd = kfd_get_process_device_data(dev, p);
+
+	if (!pdd) {
+		mutex_unlock(&p->mutex);
+		return;
+	}
+
 	if (pdd->reset_wavefronts) {
 		dbgdev_wave_reset_wavefronts(pdd->dev, p);
 		pdd->reset_wavefronts = false;
@@ -431,7 +437,6 @@ void kfd_unbind_process_from_device(struct kfd_dev *dev, unsigned int pasid)
 	 * We don't call amd_iommu_unbind_pasid() here
 	 * because the IOMMU called us.
 	 */
-	if (pdd)
 	pdd->bound = false;
 
 	mutex_unlock(&p->mutex);