can: c_can: Add device tree support to Bosch C_CAN/D_CAN controller

Add device tree support to C_CAN/D_CAN controller and usage details
are added to device tree documentation. Driver was tested on AM335x
EVM.

Signed-off-by: AnilKumar Ch <anilkumar@ti.com>
For the of binding doc:
Reviewed-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>