libcamera: v4l2_videodevice: Improve toColorSpace() readability

Wrap V4L2Device::toColorspace() inside a private static member
function in V4L2VideoDevice class. It improves readability in
setting the colorspace for V4L2DeviceFormat.

No functional changes intended.

Signed-off-by: Umang Jain <umang.jain@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>

include/libcamera/internal/v4l2_videodevice.h

@@ -268,6 +268,9 @@ private:
 
 	void watchdogExpired();
 
+	template<typename T>
+	static std::optional<ColorSpace> toColorSpace(const T &v4l2Format);
+
 	V4L2Capability caps_;
 	V4L2DeviceFormat format_;
 	const PixelFormatInfo *formatInfo_;