ARM: mach-shmobile: Fix ag5evm compilation by including linux/videodev2.h

The board file uses a 4CC defined in linux/videodev2.h. Include the
header to fix

arch/arm/mach-shmobile/board-ag5evm.c:262: error: 'V4L2_PIX_FMT_RGB565'
undeclared here (not in a function)

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>