Fix the following compilation failure:

linux-2.6/drivers/media/video/mt9m032.c: In function '__mt9m032_get_pad_crop':
linux-2.6/drivers/media/video/mt9m032.c:337: error: implicit declaration of function 'v4l2_subdev_get_try_crop'
linux-2.6/drivers/media/video/mt9m032.c:337: warning: return makes pointer from integer without a cast
linux-2.6/drivers/media/video/mt9m032.c: In function '__mt9m032_get_pad_format':
linux-2.6/drivers/media/video/mt9m032.c:359: error: implicit declaration of function 'v4l2_subdev_get_try_format'
linux-2.6/drivers/media/video/mt9m032.c:359: warning: return makes pointer from integer without a cast
linux-2.6/drivers/media/video/mt9m032.c: In function 'mt9m032_probe':
linux-2.6/drivers/media/video/mt9m032.c:767: error: 'struct v4l2_subdev' has no member named 'entity'
linux-2.6/drivers/media/video/mt9m032.c:826: error: 'struct v4l2_subdev' has no member named 'entity'
linux-2.6/drivers/media/video/mt9m032.c: In function 'mt9m032_remove':
linux-2.6/drivers/media/video/mt9m032.c:842: error: 'struct v4l2_subdev' has no member named 'entity'
make[4]: *** [drivers/media/video/mt9m032.o] Error 1

by adding a dependency on VIDEO_V4L2_SUBDEV_API.
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>