media: v4l2-ctrls-api.c: move ctrl->is_new = 1 to the correct line

The patch that fixed string control support somehow got mangled when it was
merged in mainline: the added line ended up in the wrong place.

Fix this.

Fixes: 73278d48 ("media: v4l2-ctrls-api.c: add back dropped ctrl->is_new = 1")
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>