ARM: at91/dt: at91sam9263: Add CAN device nodes

Add the missing CAN devices node including their pin muxing. The required
clock node already exists.

Signed-off-by: Alexander Stein <alexander.stein@systec-electronic.com>
Acked-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>