ARM: at91: at91_dt_defconfig: enable ISI and ov2640 support

Add Atmel-isi and ov2640 driver in defconfig

Signed-off-by: Josh Wu <josh.wu@atmel.com>
[nicolas.ferre@atmel.com: make SOC_CAMERA_OV2640 selected as a module]
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Olof Johansson <olof@lixom.net>