media: atomisp: use vb2_start_streaming_called()

Don't touch q->start_streaming_called directly, use the
vb2_start_streaming_called() function instead.

Link: https://lore.kernel.org/r/bc6c24ec-72ea-64a1-9061-311cc7339827@xs4all.nl



Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>