[media] v4l2-ctrls.c: copy-and-paste error: user_to_new -> new_to_user

The new values were never copied to userspace due to this copy and paste
error. This was introduced during the rewrite of this part of the code in
commit 3219f8a362640b7e4b7e2187b1094c4e46d85aa0.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>