Dual-license drm_gpuvm to GPL-2.0 OR MIT.

diff --git a/drivers/gpu/drm/drm_gpuvm.c b/drivers/gpu/drm/drm_gpuvm.c
index 02ce6baacdad..08c088319652 100644
--- a/drivers/gpu/drm/drm_gpuvm.c
+++ b/drivers/gpu/drm/drm_gpuvm.c
@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: GPL-2.0-only
+// SPDX-License-Identifier: GPL-2.0 OR MIT
 /*
  * Copyright (c) 2022 Red Hat.
  *

The above SPDX License Identifier change is incorrect and no longer
valid.  The change misunderstood the syntax of SPDX license identifiers
and boolean operations.  GPL-2.0-only is the name of the license and means
GPL 2.0 only, as opposed to GPL 2.0 or later.  The "only" does not
refer to restrictions on other licenses in the identifier and should not have been
removed.  The hyphens designated that the name was a single unit.
The SPDX License Identifier boolean operators, such as OR, are a separate layer
of syntax. 

The SPDX License Identifier should be

GPL-2.0-only OR MIT

Thanks, David