media: v4l: ioctl: Set bus_info in v4l_querycap()

The bus_info field is set by most drivers based on the type of the device
bus as well as the name of the device. Do this in v4l_querycap() so
drivers don't need to. This keeps compatibility with non-default and silly
bus_info.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>