hulk inclusion
category: bugfix
bugzilla: 13690
CVE: CVE-2019-16230

-------------------------------------------------

check the alloc_workqueue return value in radeon_crtc_init()
to avoid null-ptr-deref.
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>
Reviewed-by: NHanjun Guo <guohanjun@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>