libcamera: v4l2_videodevice: provide hasMediaController()

The V4L2Capability has helpers to interogate the capabilities
of a device.

V4L2VideoDevice::enumPixelformats accesses the raw capabilites to check
if the device is supported by a MediaController device.

Provide a helper, and update the usage.

Reviewed-by: Naushir Patuck <naush@raspberrypi.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

include/libcamera/internal/v4l2_videodevice.h

@@ -109,6 +109,10 @@ struct V4L2Capability final : v4l2_capability {
 	{
 		return device_caps() & V4L2_CAP_STREAMING;
 	}
+	bool hasMediaController() const
+	{
+		return device_caps() & V4L2_CAP_IO_MC;
+	}
 };
 
 class V4L2BufferCache