media: imx: fix compiler warning

drivers/staging/media/imx/imx-media-capture.c: In function 'vidioc_querycap':
drivers/staging/media/imx/imx-media-capture.c:76:2: warning: 'strncpy' output truncated copying 15 bytes from a string of length 17 [-Wstringop-truncation]
  strncpy(cap->driver, "imx-media-capture", sizeof(cap->driver) - 1);
  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Steve Longerbeam <steve_longerbeam@mentor.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>