drm/amdgpu: add missing license to dpcs_3_0_0 headers

MIT.
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/include/asic_reg/dcn/dpcs_3_0_0_offset.h

+// SPDX-License-Identifier: MIT
+/*
+ * Copyright (C) 2020 Advanced Micro Devices, Inc.
+ *
+ * Authors: AMD
+ */
+
 #ifndef _dpcs_3_0_0_OFFSET_HEADER
 #define _dpcs_3_0_0_OFFSET_HEADER
 

drivers/gpu/drm/amd/include/asic_reg/dcn/dpcs_3_0_0_sh_mask.h

+// SPDX-License-Identifier: MIT
+/*
+ * Copyright (C) 2020 Advanced Micro Devices, Inc.
+ *
+ * Authors: AMD
+ */
+
 #ifndef _dpcs_3_0_0_SH_MASK_HEADER
 #define _dpcs_3_0_0_SH_MASK_HEADER