media: rename VFL_TYPE_GRABBER to _VIDEO

We currently have the following devnode types:

enum vfl_devnode_type {
        VFL_TYPE_GRABBER        = 0,
        VFL_TYPE_VBI,
        VFL_TYPE_RADIO,
        VFL_TYPE_SUBDEV,
        VFL_TYPE_SDR,
        VFL_TYPE_TOUCH,
        VFL_TYPE_MAX /* Shall be the last one */
};

They all make sense, except for the first: GRABBER really refers to /dev/videoX
devices, which can be capture, output or m2m, so 'grabber' doesn't even refer to
their function anymore.

Let's call a spade a spade and rename this to VFL_TYPE_VIDEO.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>