media: v4l2-fwnode: Add a deprecation note in the old ACPI parsing example

 * underneath the fwnode identified by the previous tuple, etc. until you

 * reached the fwnode you need.

 *

 * An example with a graph, as defined in Documentation/acpi/dsd/graph.txt:

 * THIS EXAMPLE EXISTS MERELY TO DOCUMENT THIS FUNCTION. DO NOT USE IT AS A

 * REFERENCE IN HOW ACPI TABLES SHOULD BE WRITTEN!! See documentation under

 * Documentation/acpi/dsd instead and especially graph.txt,

 * data-node-references.txt and leds.txt .

 *

 *	Scope (\_SB.PCI0.I2C2)

 *	{