can: xilinx_can: Add support for CANFD FD frames

CANFD IP supports both CAN and CAN FD frames,
Existing driver supports only CAN frames, This patch
adds support for CAN FD frames.
Signed-off-by: Naga Sureshkumar Relli <naga.sureshkumar.relli@xilinx.com>
Signed-off-by: Appana Durga Kedareswara rao <appana.durga.rao@xilinx.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>