[ Upstream commit 55611b507fd6453d26030c0c0619fdf0c262766d ]

Check if irq_src is NULL to avoid dereferencing a NULL pointer,
for MES ring is uneccessary to recieve an interrupt notification.
Signed-off-by: NJack Xiao <Jack.Xiao@amd.com>
Acked-by: NAlex Deucher <alexander.deucher@amd.com>
Reviewed-by: NHawking Zhang <Hawking.Zhang@amd.com>
Reviewed-by: NChristian König <christian.koenig@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>