media: saa7134: Remove unnecessary INIT_LIST_HEAD()

The list_head saa7134_devlist is initialized statically.
It is unnecessary to initialize by INIT_LIST_HEAD().

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>