drm/amdgpu: make the CTX ioctl thread-safe

The existing locks were protecting the list, but not the elements.

v2: rename hlock to lock

Signed-off-by: Marek Olšák <marek.olsak@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Jammy Zhou <Jammy.Zhou@amd.com>
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
index 65246abc..cef3a43 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
@@ -1056,7 +1056,7 @@
 	struct amdgpu_device *adev;
 	struct idr ctx_handles;
 	/* lock for IDR system */
-	struct mutex hlock;
+	struct mutex lock;
 };
 
 /*