V4L/DVB (4922): Add usbvision driver

This patch adds usbvision into V4L/DVB HG tree.
Usbvision driver is a GPL driver, made by:
	Joerg Heckenbach <joerg@heckenbach-aw.de>
		and
	Dwaine Garden <DwaineGarden@rogers.com>
V4L2 migration made by:
	Thierry Merle <thierry.merle@free.fr>
Kconfig/Makefile scripts by:
	Mauro Carvalho Chehab <mchehab@infradead.org>

Signed-off-by: Joerg Heckenbach <joerg@heckenbach-aw.de>
Signed-off-by: Dwaine Garden <dwainegarden@rogers.com>
Signed-off-by: Thierry Merle <thierry.merle@free.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>