drm/radeon: fix error handling in radeon_driver_open_kms

stable inclusion
from stable-v5.10.94
commit 7bb99c7e13f8417f81247b2acea8ceaae0c5afb3
bugzilla: https://gitee.com/openeuler/kernel/issues/I531X9

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=7bb99c7e13f8417f81247b2acea8ceaae0c5afb3



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commit 4722f463 upstream.

The return value was never initialized so the cleanup code executed when
it isn't even necessary.

Just add proper error handling.

Fixes: ab50cb9d ("drm/radeon/radeon_kms: Fix a NULL pointer dereference in radeon_driver_open_kms()")
Signed-off-by: Christian König <christian.koenig@amd.com>
Tested-by: Jan Stancek <jstancek@redhat.com>
Tested-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>
Acked-by: Xie XiuQi <xiexiuqi@huawei.com>