media: staging/imx: Use a shorter name for driver

Currently v4l2-compliance tool returns the following output:

Compliance test for imx-media-captu device /dev/video0:

Driver Info:
        Driver name      : imx-media-captu
        Card type        : imx-media-capture
...

The driver name string is limited to 16 characters, so provide
a shorter name so that we can have a better output.

While at it, use the same shorter name for driver and card.

Signed-off-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>