drm/radeon: fix incorrrect SPDX-License-Identifiers

drm/radeon: fix incorrrect SPDX-License-Identifiers

[ Upstream commit 5d23bf70ccacf2d728e767542df60fac8daac1a3 ]

radeon is MIT.  This were incorrectly changed in
commit 4518740dfae2 ("License cleanup: add SPDX GPL-2.0 license identifier to files with no license")
and
commit 34602d9d9ac6 (".gitignore: add SPDX License Identifier")
and:
commit af50a7e88245 ("treewide: Add SPDX license identifier - Makefile/Kconfig")

Fixes: 34602d9d9ac6 (".gitignore: add SPDX License Identifier")
Fixes: af50a7e88245 ("treewide: Add SPDX license identifier - Makefile/Kconfig")
Fixes: 4518740dfae2 ("License cleanup: add SPDX GPL-2.0 license identifier to files with no license")
Bug: https://gitlab.freedesktop.org/drm/amd/-/issues/2053
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>