[media] v4l2-pci-skeleton: add a V4L2 PCI skeleton driver

This example driver uses all the latest frameworks and can serve as a
starting point for a new V4L2 PCI driver.

Originally written for a presentation on how to use V4L2 frameworks
during FOSDEM 2014.
Signed-off-by: NHans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: NMauro Carvalho Chehab <m.chehab@samsung.com>

Documentation/video4linux/v4l2-framework.txt

@@ -34,6 +34,10 @@ So this framework sets up the basic building blocks that all drivers
 need and this same framework should make it much easier to refactor
 common code into utility functions shared by all drivers.
 
+A good example to look at as a reference is the v4l2-pci-skeleton.c
+source that is available in this directory. It is a skeleton driver for
+a PCI capture card, and demonstrates how to use the V4L2 driver
+framework. It can be used as a template for real PCI video capture driver.
 
 Structure of a driver
 ---------------------