can: netlink: remove redundant check in can_validate()

can: netlink: remove redundant check in can_validate()

can_validate() does a first check:

|	if (is_can_fd) {
|		if (!data[IFLA_CAN_BITTIMING] || !data[IFLA_CAN_DATA_BITTIMING])
|			return -EOPNOTSUPP;
|	}

If that first if succeeds, we know that if is_can_fd is true then
data[IFLA_CAN_BITTIMING is set.

However, the next if switch does not leverage on above knowledge and
redoes the check:

| 	if (data[IFLA_CAN_DATA_BITTIMING]) {
|		if (!is_can_fd || !data[IFLA_CAN_BITTIMING])
|		                   ^~~~~~~~~~~~~~~~~~~~~~~~
| 			return -EOPNOTSUPP;
| 	}

This patch removes that redundant check.

Link: https://lore.kernel.org/r/20210603151550.140727-2-mailhol.vincent@wanadoo.fr
Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>