can: xilinx_can: mark bit timing constants as const

This patch marks the bit timing constants as const.

Fixes: c223da68 ("can: xilinx_can: Add support for CANFD FD frames")
Link: https://lore.kernel.org/all/20220317203119.792552-1-mkl@pengutronix.de
Cc: Appana Durga Kedareswara rao <appana.durga.rao@xilinx.com>
Cc: Naga Sureshkumar Relli <naga.sureshkumar.relli@xilinx.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/xilinx_can.c

@@ -239,7 +239,7 @@ static const struct can_bittiming_const xcan_bittiming_const_canfd = {
 };
 
 /* AXI CANFD Data Bittiming constants as per AXI CANFD 1.0 specs */
-static struct can_bittiming_const xcan_data_bittiming_const_canfd = {
+static const struct can_bittiming_const xcan_data_bittiming_const_canfd = {
 	.name = DRIVER_NAME,
 	.tseg1_min = 1,
 	.tseg1_max = 16,
@@ -265,7 +265,7 @@ static const struct can_bittiming_const xcan_bittiming_const_canfd2 = {
 };
 
 /* AXI CANFD 2.0 Data Bittiming constants as per AXI CANFD 2.0 spec */
-static struct can_bittiming_const xcan_data_bittiming_const_canfd2 = {
+static const struct can_bittiming_const xcan_data_bittiming_const_canfd2 = {
 	.name = DRIVER_NAME,
 	.tseg1_min = 1,
 	.tseg1_max = 32,