drm/msm: make sure last_fence is always updated

Update last_fence in the vm-bind path instead of kernel managed path.

last_fence is used to wait for work to finish in vm_bind contexts but not
used for kernel managed contexts.

This fixes a bug where last_fence is not waited on context close leading
to faults as resources are freed while in use.

Fixes: 92395af63a99 ("drm/msm: Add VM_BIND submitqueue")
Signed-off-by: Anna Maniscalco <[e-mail]>
Patchwork: https://patchwork.freedesktop.org/patch/680080/
Message-ID: <[e-mail]>
Signed-off-by: Rob Clark <[e-mail]>

drivers/gpu/drm/msm/msm_gem_submit.c

···
 					 submit->user_fence,
 					 DMA_RESV_USAGE_BOOKKEEP,
 					 DMA_RESV_USAGE_BOOKKEEP);
+
+		last_fence = vm->last_fence;
+		vm->last_fence = dma_fence_unwrap_merge(submit->user_fence, last_fence);
+		dma_fence_put(last_fence);
+
 		return;
 	}
 
···
 			dma_resv_add_fence(obj->resv, submit->user_fence,
 					   DMA_RESV_USAGE_READ);
 	}
-
-	last_fence = vm->last_fence;
-	vm->last_fence = dma_fence_unwrap_merge(submit->user_fence, last_fence);
-	dma_fence_put(last_fence);
 }
 
 static int submit_bo(struct msm_gem_submit *submit, uint32_t idx,