[media] saa7164: make buffer smaller

This isn't a runtime bug, it's just to make static checkers happy.

In vidioc_querycap() we copy a saa7164_dev ->name driver array into a
v4l2_capability -> driver array.  The ->driver array is only 16 chars
long so ->name also can't be more than 16 characters.

The ->name gets set in v4l2_capability() and it always is less than 16
characters so we can easily make the buffer smaller.

Signed-off-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>