The patch adding support for dynamically allocated arrays accidentally
dropped the line setting ctrl->is_new to 1, thus new string values were
always ignored.

Fixes: fb582cba ("media: v4l2-ctrls: add support for dynamically allocated arrays.")
Reported-by: NAlice Yuan <alice.yuan@nxp.com>
Signed-off-by: NHans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: NMauro Carvalho Chehab <mchehab@kernel.org>