Make VIDIOC_[GS]_CTRL work

v4l2_control.value was left uninitialised for the VIDIOC_S_CTRL IOCTL. Fix
that.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Integer64 and string controls can't be accessed using VIDIOC_[GS]_CTRL

So don't even try.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>