video: Remove pnx4008 driver

This patch removes the video driver for pnx4008. The architecture is being
removed via the arm-soc tree.

Signed-off-by: Roland Stigge <stigge@antcom.de>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>